ISO 20683-2:2016
(Main)Aircraft ground equipment — Design, testing and maintenance requirements for nose gear towbarless towing vehicle (TLTV) — Part 2: Regional aircraft
Aircraft ground equipment — Design, testing and maintenance requirements for nose gear towbarless towing vehicle (TLTV) — Part 2: Regional aircraft
ISO 20683-2:2016 is applicable to towbarless aircraft towing vehicles (TLTVs) interfacing with the nose landing gear of civil transport aircraft with a maximum ramp mass comprised between 10 000 and 50 000 kg (22 000 and 110 000 lb), commonly designated as "regional aircraft." The requirements for main line transport aircraft with a higher maximum ramp mass are specified in ISO 20683‑1. It is not applicable to TLTVs which were manufactured before its date of publication. It specifies general design requirements, testing and evaluation requirements, maintenance, calibration, documentation, records, tracing and accountability requirements in order to ensure that the loads induced by the tow vehicle will not exceed the design loads of the nose gear or its steering system, or reduce the certified safe life limit of the nose gear, or induce a stability problem during aircraft push back and/or maintenance towing operations. It specifies requirements and procedures for towbarless tow vehicles (TLTVs) intended for aircraft pushback and gate relocation or maintenance towing only. It is not intended to allow for dispatch (operational) towing (see Clause 3). Dispatch towing imposes greater loads on nose gears and aircraft structure due to the combination of speed and additional passenger, cargo, and fuel loads. It does not apply to towbarless towing vehicles interfacing with aircraft main landing gear.
Matériels au sol pour aéronefs — Exigences de conception, essais et entretien pour tracteur sans barre de train avant (TLTV) — Partie 2: Aéronefs régionaux
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INTERNATIONAL ISO
STANDARD 20683-2
Second edition
2016-08-15
Aircraft ground equipment —
Design, testing and maintenance
requirements for nose gear
towbarless towing vehicle (TLTV) —
Part 2:
Regional aircraft
Matériels au sol pour aéronefs — Exigences de conception, essais et
entretien pour tracteur sans barre de train avant (TLTV) —
Partie 2: Aéronefs régionaux
Reference number
ISO 20683-2:2016(E)
©
ISO 2016
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ISO 20683-2:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved
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ISO 20683-2:2016(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Design requirements . 4
4.1 General . 4
4.2 Towing loads . 4
4.3 Pick-up and holding system . 5
4.4 Oversteering protection . 5
4.5 Testing operations. 5
4.5.1 Snubbing and jerking . 5
4.5.2 Vibrations . 6
4.5.3 Aircraft braking . 6
4.5.4 Stability . 6
4.6 Vehicle classification . 6
4.7 Placarding . 6
5 Testing requirements . 7
5.1 General . 7
5.2 Static load tests . 7
5.3 Dynamic load tests . 7
5.4 Operational tests . 8
5.5 Aircraft braking . 8
6 Computer modelling . 9
6.1 General . 9
6.2 Validation . 9
7 Maintenance .10
7.1 General .10
7.2 Maintenance manual .10
7.3 Requirements .10
7.4 Calibration .11
7.5 Special tools .11
7.6 Training .12
7.7 Maintenance records .12
8 Quality control .12
9 Traceability and accountability .13
10 Modifications .14
11 Operating instructions .14
Bibliography .15
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ISO 20683-2:2016(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.
The committee responsible for this document is ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 9, Air cargo and ground equipment.
This second edition cancels and replaces the first edition of ISO 20683-2:2004, which has been
technically revised.
A list of all parts in the ISO 20683 series can be found on the ISO website.
iv © ISO 2016 – All rights reserved
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ISO 20683-2:2016(E)
Introduction
This document specifies design, testing, maintenance and associated requirements to be applied on
towbarless aircraft towing vehicles to be used on regional civil transport aircraft in order to ensure
their operation will not result in damage to aircraft nose landing gears, their steering systems or
associated aircraft structure.
Throughout this document, the minimum essential criteria are identified by the use of the keyword
“shall.” Other recommended criteria are identified by the use of the keyword “should” and, while not
mandatory, are considered to be of primary importance in providing safe and serviceable towbarless
tractors. Alternative solutions may be adopted only after careful consideration, extensive testing and
thorough service evaluation have shown them to be equivalent.
© ISO 2016 – All rights reserved v
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INTERNATIONAL STANDARD ISO 20683-2:2016(E)
Aircraft ground equipment — Design, testing and
maintenance requirements for nose gear towbarless
towing vehicle (TLTV) —
Part 2:
Regional aircraft
1 Scope
This document is applicable to towbarless aircraft towing vehicles (TLTVs) interfacing with the nose
landing gear of civil transport aircraft with a maximum ramp mass comprised between 10 000 and
50 000 kg (22 000 and 110 000 lb), commonly designated as “regional aircraft.” The requirements for
main line transport aircraft with a higher maximum ramp mass are specified in ISO 20683-1. It is not
applicable to TLTVs which were manufactured before its date of publication.
It specifies general design requirements, testing and evaluation requirements, maintenance, calibration,
documentation, records, tracing and accountability requirements in order to ensure that the loads
induced by the tow vehicle will not exceed the design loads of the nose gear or its steering system, or
reduce the certified safe life limit of the nose gear, or induce a stability problem during aircraft push
back and/or maintenance towing operations.
This document specifies requirements and procedures for towbarless tow vehicles (TLTVs) intended
for aircraft pushback and gate relocation or maintenance towing only. It is not intended to allow for
dispatch (operational) towing (see Clause 3). Dispatch towing imposes greater loads on nose gears and
aircraft structure due to the combination of speed and additional passenger, cargo, and fuel loads.
This document does not apply to towbarless towing vehicles interfacing with aircraft main landing gear.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
NOTE TLTV designers should also take into account the requirements of documents referenced in the
Bibliography.
ISO 6966-1, Aircraft ground equipment — Basic requirements — Part 1: General design requirements
ISO 6966-2, Aircraft ground equipment — Basic requirements — Part 2: Safety requirements
Federal Aviation Regulations (FAR) 14 CFR Part 25, Airworthiness Standards: Transport category
1)
airplanes, paragraphs 25.301, Loads, and 25.509, Towing loads
Certification Specifications and Acceptable Means of Compliance for Large Aeroplanes CS-25, paragraphs
2)
25.301, Loads, 25.509, Towing loads, 25.745(d), Nose-wheel steering, and AMC 25.745(d)
1) FAR Part 25 constitutes the U.S.A. government transport aircraft airworthiness regulations and can be obtained
from US Government Printing Office, Mail Stop SSOP, Washington DC 20402-9328, U.S.A.
2) EASA CS25 constitute the European governments transport aircraft airworthiness regulations, and can be
obtained from European Aviation Safety Agency: Ottoplatz 1, D-50679 Cologne, Germany - http://easa.europa.
eu/official-publication/.
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ISO 20683-2:2016(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
main line aircraft
civil passenger and/or freight transport aircraft with a maximum ramp mass over 50 000 kg (110 000 lb)
3.2
regional aircraft
civil passenger and/or freight transport aircraft with a maximum ramp mass between 10 000 kg (22
000 lb) and 50 000 kg (110 000 lb)
3.3
maximum ramp mass
maximum ramp weight
MRW
maximum mass allowable for an aircraft type when leaving its parking position either under its own
power or towed, comprising maximum structural take-off mass (MTOW) and taxiing fuel allowance
3.4
pushback
moving a fully loaded aircraft [up to maximum ramp mass (MRW)] from the parking position to the
taxiway
Note 1 to entry: Movement includes pick-up, pushback with turn, a stop, a short push or tow to align aircraft and
nose wheels, and release. Engines may or may not be operating. Aircraft movement is similar to a conventional
pushback operation with a tow bar. Typical speed does not exceed 10 km.h-1 (6 mph).
3.5
maintenance towing
movement of an aircraft for maintenance/remote parking purposes (e.g. from the parking position to a
maintenance hangar)
Note 1 to entry: The aircraft is typically unloaded with minimal fuel load (reference light gross weight, LGW),
with speeds up to 32 km.h-1 (20 mph).
3.6
gate relocation towing
movement of an aircraft from one parking position to an adjacent one or one in the same general area
Note 1 to entry: The aircraft is typically unloaded with minimal fuel load [reference light gross weight (LGW)],
with speeds intermediate between pushback and maintenance towing.
3.7
dispatch towing
operational towing
towing a revenue aircraft [loaded with passengers, fuel, and cargo up to maximum ramp mass (MRW)],
from the terminal gate/remote parking area, to a location near the active runway, or conversely,
possibly covering several kilometres with speeds up to or over 32 km.h-1 (20 mph), with several starts,
stops and turns
Note 1 to entry: Replaces typical taxiing operations prior to take-off or after landing.
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ISO 20683-2:2016(E)
Note 2 to entry: In the definitions of the towing modes, the frequency of operation has not been included. This
should not be interpreted to mean that no limitations are present. For limitations on the frequency of pushback
and maintenance operations, refer to the appropriate airframe manufacturer’s documentation or consult directly
with the airframe manufacturer.
3.8
towbarless towing vehicle
TLTV
towing vehicle acting without tow bar on an aircraft’s nose landing gear
3.9
nose landing gear
NLG
aircraft nose landing gear in a tricycle landing gear layout
3.10
light gross weight
LGW
reference aircraft mass for combined testing of the vehicle and aircraft, defined as the manufacturer’s
operating empty mass of the aircraft type concerned, plus fuel remaining in the tanks on landing (10 %
to 20 % of total tanks capacity)
3.11
heavy gross weight
HGW
reference aircraft mass for combined testing of the vehicle and aircraft, defined as the manufacturer’s
operating empty mass of the aircraft concerned, plus at least 50 % of the maximum total fuel tanks
capacity on the type, or its equivalent in mass (payload may be accounted if present, providing aircraft
balance condition remains within limits)
3.12
maximum limits
limits (fore and aft tractive force, torsional or angular) established by the airframe manufacturer as
not-to-exceed values intended to preclude possible damage to nose landing gear or structure
Note 1 to entry: Maximum limits are established by airframe manufacturer’s documentation and may be different
for towbarless or tow bar towing operations. All aircraft load limits are limit loads as defined in FAR/EASA CS
paragraph 25.301 (a).
3.13
operational limits
limits (fore and aft tractive force, torsional or angular) which are set at a lesser value than the maximum
limits established by the airframe manufacturer
3.14
aircraft family
grouping of aircraft types or subtypes, defined by their manufacturer, for which the same maximum
limits may be applied
Note 1 to entry: A family usually encompasses all sub-types of a given type, but may also include other types.
Testing for one (usually the lightest) model of the family results in towbarless towing approval for the whole
family. See airframe manufacturers towbarless towing evaluation documentation.
3.15
TLTV setting
grouping of aircraft types or sub-types, defined by the TLTV manufacturer, for which a single
operational limits setting is used
Note 1 to entry: A single TLTV setting usually encompasses aircraft types or sub-types, which may be produced
by different airframe manufacturers, in a same defined MRW range.
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ISO 20683-2:2016(E)
3.16
drag load
towforce
total force from the tow vehicle on the nose gear tires in the “x” axis
3.17
X axis
fore and aft axis of the tow vehicle, parallel to the ground
3.18
oversteer
exceedence of maximum torsional load or angular limits where potential damage to the nose landing
gear structure or steering system could take place
Note 1 to entry: These limits are defined in the appropriate airframe manufacturer’s documentation. Torsional
load limits typically occur after exceeding angular limits, but may occur before the angular limit is reached (e.g.
nose gear hydraulic system bypass failure).
3.19
snubbing
sudden relief and reapplication of acceleration/deceleration loads while TLTV and aircraft are in motion
3.20
jerking
sudden application of push/pull forces from a complete stop
4 Design requirements
4.1 General
4.1.1 Towbarless tow vehicles (TLTVs) shall comply with the applicable general requirements of
ISO 6966-1 and safety requirements of ISO 6966-2.
4.1.2 Airframe manufacturers should provide information for each aircraft type which allows TLTV
manufacturers or airlines to self-test or evaluate the towbarless tow vehicles themselves. Refer to the
airframe manufacturer’s documentation for evaluation requirements and detailed testing procedures
that may be different from or additional to those contained in this document.
4.1.3 TLTV manufacturers should prepare and provide customers or regulatory agencies, as required,
with a certificate of compliance or equivalent documentation, as evidence that successful testing and
evaluation of a specific tow vehicle/aircraft type combination has been completed in accordance with
this document and/or the applicable airframe manufacturer’s documentation. This certificate shall
allow the use of the vehicle on specifically designated aircraft model types. The certificate should be
established under an appropriate quality control program meeting the requirements of ISO 9001 or
equivalent pertinent industry standard.
4.1.4 Towbarless towing vehicles shall, either by intrinsic design or through appropriate load limiting
devices, ensure that the following maximum limits are not exceeded.
4.2 Towing loads
4.2.1 The push and pull towing forces induced by the TLTV onto the aircraft’s nose landing gear as a
result of either accelerating or braking shall be verified as per Clauses 5 and/or 6 hereafter, and shall not
at any time exceed the maximum values specified by the aircraft manufacturer.
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ISO 20683-2:2016(E)
4.2.2 Depending on the range of aircraft types the TLTV is compatible with, preset towing load values
may be used for a number of aircraft types or sub-types in a given MRW range. In this case, each TLTV
setting shall comply with the maximum limits specified by the manufacturer(s) of the designated aircraft
types, sub-types, or family(s) thereof as defined by the aircraft manufacturers, and each TLTV setting
shall be subjected to a separate verification.
4.3 Pick-up and holding system
4.3.1 The TLTV’s nose landing gear pick-up/release device should operate in a smooth and continuous
manner. Abrupt or oscillating loads during the pick-up/release sequence should not occur. It should be
designed to minimize the loads during the pick-up/release sequence. The drag loads induced during
pick-up/release should fall well below the “peak” loads experienced during a typical operation.
4.3.2 The maximum loads induced by pick-up and release sequences shall be measured either on an
aircraft or on a fixture representative of the nose gear geometry. The vertical load on the nose gear or
fixture shall be equal to the vertical load used for fatigue justification (refer to the appropriate airframe
manufacturer’s documentation). The maximum lift (height above the ground) of the nose gear shall not
exceed the values given in the airframe manufacturer’s documentation if such values are provided.
4.4 Oversteering protection
4.4.1 The maximum angular or torsional load limits stated by the aircraft’s manufacturer in the event
of oversteering shall not at any time be exceeded. See aircraft manufacturer’s TLTV assessment criteria
document.
4.4.2 This may be achieved either by oversteer protection built into the TLTV, or by an oversteer
alerting system being provided.
4.4.3 Oversteer protection may be achieved either by intrinsic design precluding the possibility of
either limit being reached or exceeded, or by a fail-safe oversteer protection system ensuring they shall
not be exceeded. Oversteer alerting shall consist in an appropriate fail-safe warning system installed on
the TLTV, providing the driver with unmistakable indication that one of the maximum limits was reached.
EASA CS requirements:
For aircraft registered or operated under EASA CS-25 paragraph 25.745(d) and associated
AMC 25.745(d), requires the TLTV manufacturers to provide a Declaration of Compliance (4.1.3) of their
unit’s oversteer protection or oversteer alerting system(s) with the present International Standard and
the criteria published by the manufacturer of each aircraft type for which it is intended, and the aircraft
manufacturers to list in their appropriate documentation the TLTV models that were specifically
accepted for each aircraft type based on this Declaration of Compliance.
4.4.4 No testing of the TLTV oversteer protection or alerting systems shall be performed on an in-
service aircraft, in order to preclude any possible damage to the NLG structure or steering system. Such
testing should be accomplished with a suitable ground testing device representative of the specific
aircraft model for which the TLTV is intended, or through appropriate numeric simulation demonstration.
4.5 Testing operations
4.5.1 Snubbing and jerking
Snubbing and jerking effects or movements should be avoided during testing.
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ISO 20683-2:2016(E)
4.5.2 Vibrations
If severe or abnormal vibrations occur, testing should be discontinued and the cause determined.
4.5.3 Aircraft braking
The aircraft brakes should not be used while the aircraft is being towed by a TLTV, except in an
emergency situation. Aircraft braking, while the aircraft is under tow, may result in loads exceeding
the aircraft’s design loads and may result in structural damage and/or nose gear collapse. For these
reasons, it is recommended that airlines take appropriate steps to preclude aircraft braking during
normal towbarless towing. The carrier’s or airframe manufacturer’s maintenance manual and
operational procedures shall be complied with.
4.5.4 Stability
4.5.4.1 Attention shall be paid to aircraft stability. Stability may be affected by aircraft type, mass, centre
of gravity location, weather condition, runway roughness, and slope. Stability shall be demonstrated by
tests in accordance with the airframe manufacturer documentation.
4.5.4.2 The testing shall be conducted under maximum speed capability of the vehicle.
4.5.4.3 If a lateral instability is detected, a margin of 5 km/h (3 mph) shall be maintained between the
speed at the beginning of instability and the maximum towing speed.
4.5.4.4 With minimal static load on the nose landing gear sufficient to move the airplane, no pitch
oscillation of the aircraft shall occur, such that it would extend the shock absorber beyond the allowable
strut extension in the ground mode.
4.5.4.5 Proper operational procedures shall be defined and followed to ensure vehicle and airplane
stability.
4.6 Vehicle classification
The TLTV model shall be classified according to its intended use, and tested or evaluated accordingly,
as either
a) category I: pushback only, or
b) category II: maintenance towing only, or
c) category III: both pushback and maintenance.
4.7 Placarding
Limitations and warnings imposed by all conditions shall be placarded in a location readily visible to
the tow vehicle driver, including but not necessarily limited to
a) classification category defined in 4.6,
b) types of aircraft the TLTV is qualified for (by TLTV setting if applicable),
c) maximum allowable speed, and
d) maximum allowable towing angle, etc.
6 © ISO 2016 – All rights reserved
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ISO 20683-2:2016(E)
5 Testing requirements
5.1 General
5.1.1 The following tests shall be performed to provide verification that the loads induced by the TLTV
do not exceed the allowable maximum limits, and the operation of the unit in an operational pushback
environment does not result in events potentially jeopardizing aircraft safety.
5.1.2 Dynamic numeric simulation may be used instead of part of the specified tests, unless prohibited
by airframe manufacturer’s documentation, and provided it
...
DRAFT INTERNATIONAL STANDARD
ISO/DIS 20683-2
ISO/TC 20/SC 9 Secretariat: AFNOR
Voting begins on: Voting terminates on:
2015-11-05
2016-02-05
Aircraft ground equipment — Design, test and
maintenance for towbarless towing vehicles (TLTV)
interfaced with nose-landing gear —
Part 2:
Regional aircraft
Matériels au sol pour aéronefs — Conception, essais et entretien des tracteurs sans barre (TLTV)
s’accouplant au train d’atterrissage avant —
Partie 2: Aéronefs régionaux
ICS: 49.100
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 20683-2:2015(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2015
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ISO/DIS 20683-2:2015(E) ISO/DIS 20683-2(E)
Contents Page
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Design requirements . 4
4.1 General . 4
4.2 T ow ing loads . 4
4.3 Oversteering protection . 5
4.4 Vehicle classification . 5
4.5 Placarding . 6
5 Testing requirements . 6
5.1 General . 6
5.2 Static load tests . 7
5.3 Dynamic load tests . 7
5.4 Operational tests . 8
5.5 Aircraft braking . 8
6 Computer modeling . 8
6.1 General . 8
6.2 Validation . 9
7 Quality control . 9
8 Traceability and accountability . 13
9 Operating instructions . 13
Bibliography . 15
COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2015 – All rights reserved
© ISO 2015 – All rights reserved iii
---------------------- Page: 2 ----------------------
ISO/DIS 20683-2(E)
Contents Page
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Design requirements . 4
4.1 General . 4
4.2 Towing loads . 4
4.3 Oversteering protection . 5
4.4 Vehicle classification . 5
4.5 Placarding . 6
5 Testing requirements . 6
5.1 General . 6
5.2 Static load tests . 7
5.3 Dynamic load tests . 7
5.4 Operational tests . 8
5.5 Aircraft braking . 8
6 Computer modeling . 8
6.1 General . 8
6.2 Validation . 9
7 Quality control . 9
8 Traceability and accountability . 13
9 Operating instructions . 13
Bibliography . 15
© ISO 2015 – All rights reserved iii
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ISO/DIS 20683-2(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 20683-2(E) was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,
Subcommittee SC 9, Air cargo and ground equipment.
This second/third/. edition cancels and replaces the first/second/. edition (ISO 20683-2:2004), [clause(s) /
subclause(s) / table(s) / figure(s) / annex(es)] of which [has / have] been technically revised.
ISO 20683 consists of the following parts, under the general title Aircraft ground equipment — Design, testing
and maintenance requirements for nose gear towbarless towing vehicle (TLTV):
Part 1: Main line aircraft
Part 2: Regional aircraft
iv © ISO 2015 – All rights reserved
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ISO/DIS 20683-2(E)
Introduction
This International Standard, constituting Part 2 of International Standard ISO 20683, Aircraft ground
equipment — Nose gear towbarless towing vehicles (TLTV) — Design, testing and maintenance requirements,
specifies design, testing, maintenance and associated requirements to be applied on towbarless aircraft
towing vehicles to be used on regional civil transport aircraft in order to ensure their operation cannot result in
damage to aircraft nose landing gears, their steering systems, or associated aircraft structure.
Throughout this International Standard, the minimum essential criteria are identified by the use of the key
word “shall”. Other recommended criteria are identified by the use of the key word “should” and, while not
mandatory, are considered to be of primary importance in providing safe and serviceable towbarless tractors.
Alternative solutions may be adopted only after careful consideration, extensive testing and thorough service
evaluation have shown them to be equivalent.
© ISO 2015 – All rights reserved v
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DRAFT INTERNATIONAL STANDARD ISO/DIS 20683-2(E)
Aircraft ground equipment — Design, testing and maintenance
requirements for nose gear towbarless towing vehicle (TLTV) —
Part 2(E): Regional aircraft
1 Scope
This International Standard is applicable to towbarless aircraft towing vehicles (TLTVs) interfacing with the
nose landing gear of civil transport aircraft with a maximum ramp mass comprised between 10 000 kg and
50 000 kg (22 000 lb and 110 000 lb), commonly designated as "regional aircraft". The requirements for main
line transport aircraft with a higher maximum ramp mass are specified in ISO 20683-1 (Part 1). It is not
applicable to TLTVs which were manufactured before its date of publication.
It specifies general design requirements, testing and evaluation requirements, maintenance, calibration,
documentation, records, tracing and accountability requirements in order to ensure that the loads induced by
the tow vehicle will not exceed the design loads of the nose gear or its steering system, or reduce the certified
safe life limit of the nose gear, or induce a stability problem during aircraft push back and / or maintenance
towing operations.
This International Standard specifies requirements and procedures for towbarless tow vehicles (TLTVs)
intended for aircraft push-back and gate relocation or maintenance towing only. It is not intended to allow for
dispatch (operational) towing (see clause 3, Terms and definitions). Dispatch towing imposes greater loads on
nose gears and aircraft structure due to the combination of speed and additional passenger, cargo, and fuel
loads.
This International Standard does not apply to towbarless towing vehicles interfacing with aircraft main landing
gear.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
Federal Aviation Regulations (FAR) 14 CFR Part 25, Airworthiness Standards: Transport category airplanes,
1)
paragraphs 25.301, Loads, and 25.509, Towing loads .
Certification Specifications and Acceptable Means of Compliance for Large Aeroplanes CS-25, paragraphs
2)
25.301, Loads, 25.509, Towing loads, 25.745(d), Nose-wheel steering, and AMC 25.745(d) .
1) FAR Part 25 constitute the U.S.A. Government transport aircraft airworthiness Regulations, and can be obtained
from: US Government Printing Office, Mail Stop SSOP, Washington DC 20402-9328, U.S.A.
2) EASA CS25 constitute the European Governments transport aircraft airworthiness Regulations, and can be obtained
from: European Aviation Safety Agency: Ottoplatz 1, D-50679 Cologne, Germany - http://easa.europa.eu/official-
publication/.
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ISO/DIS 20683-2(E)
ISO 6966-1, Aircraft ground equipment — Basic requirements — Part 1: General requirements.
ISO 6966-2, Aircraft ground equipment — Basic requirements — Part 2: Safety requirements.
NOTE TLTV designers should also take into account the requirements of documents referenced in Bibliography.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
main line aircraft
civil passenger and/or freight transport aircraft with a maximum ramp mass over 50 000 kg (110 000 lb)
3.2
regional aircraft
civil passenger and/or freight transport aircraft with a maximum ramp mass between 10 000 kg (22 000 lb)
and 50 000 kg (110 000 lb)
3.3
maximum ramp mass
MRW
Maximum Ramp Weight
maximum mass allowable for an aircraft type when leaving its parking position either under its own power or
towed, comprising maximum structural take-off mass (MTOW) and taxiing fuel allowance
3.4
push-back
moving a fully loaded aircraft (up to maximum ramp mass (MRW)) from the parking position to the taxiway.
Movement includes pick-up, push back with turn, a stop, a short push or tow to align aircraft and nose wheels,
and release. Engines may or may not be operating. Aircraft movement is similar to a conventional push back
-1
operation with a tow bar. Typical speed does not exceed 10 km.h (6 mph)
3.5
maintenance towing
movement of an aircraft for maintenance/remote parking purposes (e.g., from the parking position to a
maintenance hangar). The aircraft is typically unloaded with minimal fuel load (reference light gross weight,
-1
LGW), with speeds up to 32 km.h (20 mph)
3.6
gate relocation towing
movement of an aircraft from one parking position to an adjacent one or one in the same general area. The
aircraft is typically unloaded with minimal fuel load (reference light gross weight, LGW), with speeds
intermediate between push back and maintenance towing
3.7
dispatch towing
operational towing
towing a revenue aircraft [loaded with passengers, fuel, and cargo up to maximum ramp mass (MRW)], from
the terminal gate/remote parking area, to a location near the active runway, or conversely. The movement
-1
may cover several kilometers with speeds up to or over 32 km.h (20 mph), with several starts, stops and
turns. Replaces typical taxiing operations prior to takeoff or after landing
NOTE In the definitions of the towing modes, the frequency of operation has not been included. This should not be
interpreted to mean that no limitations are present. For limitations on the frequency of push-back and maintenance
operations, refer to the appropriate airframe manufacturer's documentation or consult directly with the airframe
manufacturer.
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ISO/DIS 20683-2(E)
3.8
towbarless towing vehicle
TLTV
towing vehicle acting without tow bar on an aircraft’s nose landing gear
3.9
nose landing gear
NLG
aircraft nose landing gear in a tricycle landing gear layout
3.10
light gross weight
LGW
reference aircraft mass for combined testing of the vehicle and aircraft, defined as the manufacturer’s
operating empty mass of the aircraft type concerned, plus fuel remaining in the tanks on landing (10 % to
20 % of total tanks capacity)
3.11
heavy gross weight
HGW
reference aircraft mass for combined testing of the vehicle and aircraft, defined as the manufacturer’s
operating empty mass of the aircraft concerned, plus at least 50 % of the maximum total fuel tanks capacity
on the type, or its equivalent in mass (payload may be accounted if present, providing aircraft balance
condition remains within limits)
3.12
maximum limits
limits (fore and aft tractive force, torsional, or angular) established by the airframe manufacturer as
not-to-exceed values intended to preclude possible damage to nose landing gear or structure
NOTE Maximum limits are established by airframe manufacturer’s documentation and may be different for
towbarless or tow bar towing operations. All aircraft load limits are limit loads as defined in FAR/JAR paragraph 25.301 (a).
3.13
operational limits
limits (fore and aft tractive force, torsional, or angular) which are set at a lesser value than the maximum limits
established by the airframe manufacturer
3.14
aircraft family
grouping of aircraft types or subtypes, defined by their manufacturer, for which the same maximum limits may
be applied
NOTE A family usually encompasses all sub-types of a given type, but may also include other types. Testing for one
(usually the lightest) model of the family results in towbarless towing approval for the whole family. See airframe
manufacturers towbarless towing evaluation documentation.
3.15
TLTV setting
grouping of aircraft types or sub-types, defined by the TLTV manufacturer, for which a single operational limits
setting is used
NOTE A single TLTV setting usually encompasses aircraft types or sub-types, which may be produced by different
airframe manufacturers, in a same defined MRW range.
3.16
drag load
towforce
total force from the tow vehicle on the nose gear tires in the “X” axis
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ISO/DIS 20683-2(E)
3.17
"X" axis
fore and aft axis of the tow vehicle, parallel to the ground
3.18
oversteer
exceedence of maximum torsional load or angular limits where potential damage to the nose landing gear
structure or steering system could take place
NOTE These limits are defined in the appropriate airframe manufacturer’s documentation. Torsional load limits
typically occur after exceeding angular limits, but may occur before the angular limit is reached (e.g., nose gear hydraulic
system bypass failure).
3.19
snubbing
sudden relief and reapplication of acceleration/deceleration loads while TLTV and aircraft are in motion
3.20
jerking
sudden application of push/pull forces from a complete stop
4 Design requirements
4.1 General
4.1.1 Towbarless tow vehicles (TLTVs) shall comply with the applicable general requirements of
ISO 6966-1 and safety requirements of ISO 6966-2.
4.1.2 Airframe manufacturers should provide information for each aircraft type which allows TLTV
manufacturers or airlines to self-test or evaluate the towbarless tow vehicles themselves. Refer to the airframe
manufacturer's documentation for evaluation requirements and detailed testing procedures, that may be
different from or additional to those contained in this International Standard.
4.1.3 TLTV manufacturers should prepare and provide customers or regulatory agencies, as required, with
a certificate of compliance or equivalent documentation, as evidence that successful testing and evaluation of
a specific tow vehicle/aircraft type combination has been completed in accordance with this International
Standard and/or the applicable airframe manufacturer’s documentation. This certification shall allow use of the
vehicle on specifically designated aircraft models/types. The certificate should be established under an
appropriate quality control program meeting the requirements of ISO 9001 (see Bibliography) or equivalent
pertinent industry standard.
4.1.4 Towbarless towing vehicles shall, either by intrinsic design or through appropriate load limiting
devices, ensure that the following maximum limits are not exceeded.
4.2 Towing loads
4.2.1 The push and pull towing forces induced by the TLTV onto the aircraft's nose landing gear as a result
of either accelerating or braking shall be verified as per clauses 5 and/or 6 hereafter, and shall not at any time
exceed the maximum values specified by the aircraft manufacturer.
4.2.2 Depending on the range of aircraft types the TLTV is compatible with, preset towing load values may
be used for a number of aircraft types or sub-types in a given MRW range. In this case, each TLTV setting
shall comply with the maximum limits specified by the manufacturer(s) of the designated aircraft types, sub-
types, or family(s) thereof as defined by the aircraft manufacturers, and each TLTV setting shall be subjected
to a separate verification.
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ISO/DIS 20683-2(E)
4.3 Pick-up and holding system
4.2.1 The TLTV’s nose landing gear pick-up/release device should operate in a smooth and continuous
manner. Abrupt or oscillating loads during the pick-up/release sequence should not occur. It should be
designed to minimize the loads during the pick-up/release sequence. The drag loads induced during pick-
up/release should fall well below the "peak" loads experienced during a typical operation.
4.2.2 The maximum loads induced by pick-up and release sequences shall be measured either on an
aircraft or on a fixture representative of the nose gear geometry. The vertical load on the nose gear or fixture
shall be equal to the vertical load used for fatigue justification (refer to the appropriate airframe manufacturer's
documentation). The maximum lift (height above the ground) of the nose gear shall not exceed the values
given in the airframe manufacturer's documentation if such values are provided.
4.4 Oversteering protection
4.4.1 The maximum angular or torsional load limits stated by the aircraft's manufacturer in the event of
oversteering shall not at any time be exceeded. See aircraft manufacturer's TLTV assessment criteria
document.
4.4.2 This may be achieved either by oversteer protection built into the TLTV, or by an oversteer alerting
system being provided.
4.4.3 Oversteer protection may be achieved either by intrinsic design precluding the possibility of either limit
being reached or exceeded, or by a fail-safe oversteer protection system ensuring they shall not be exceeded.
Oversteer alerting shall consist in an appropriate fail-safe warning system installed on the TLTV, providing the
driver with unmistakable indication that one of the maximum limits was reached.
4.4.4 No testing of the TLTV oversteer protection or alerting systems shall be performed on an in-service
aircraft, in order to preclude any possible damage to the NLG structure or steering system. Such testing
should be accomplished with a suitable ground testing device representative of the specific aircraft model for
which the TLTV is intended, or through appropriate numeric simulation demonstration.
NOTE EASA CS requirements:
For aircraft registered or operated under EASA CS-25 paragraph 25.745(d) and associated AMC 25.745(d), requires the
TLTV manufacturers to provide a Declaration of Compliance (see clause 4.1.3) of their unit's oversteer protection or
oversteer alerting system(s) with the present International Standard and the criteria published by the manufacturer of each
aircraft type for which it is intended, and the aircraft manufacturers to list in their appropriate documentation the TLTV
models that were specifically accepted for each aircraft type based on this Declaration of Compliance.
4.5 Testing operations
4.5.1 Snubbing and jerking
Snubbing and jerking effects or movements should be avoided during testing.
4.5.2 Vibrations
If severe or abnormal vibrations occur, testing should be discontinued and the cause determined.
4.5.3 Aircraft braking
The aircraft brakes should not be used while the aircraft is being towed by a TLTV, except in an emergency
situation. Aircraft braking, while the aircraft is under tow, may result in loads exceeding the aircraft’s design
loads and may result in structural damage and/or nose gear collapse. For these reasons, it is recommended
that airlines take appropriate steps to preclude aircraft braking during normal towbarless towing. The carrier’s
or airframe manufacturer’s maintenance manual and operational procedures shall be complied with.
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ISO/DIS 20683-2(E)
4.5.4 Stability
4.5.4.1 Attention shall be paid to aircraft stability. Stability may be affected by aircraft type, mass, center
of gravity location, weather condition, runway roughness, and slope. Stability shall be demonstrated by tests in
accordance with the airframe manufacturer documentation.
4.5.4.2 The testing shall be conducted under maximum speed capability of the vehicle.
4.5.4.3 If a lateral instability is detected, a margin of 5 km/h (3 mph) shall be maintained between the
speed at the beginning of instability and the maximum towing speed.
4.5.4.4 With minimal static load on the nose landing gear sufficient to move the airplane, no pitch
oscillation of the aircraft shall occur, such that it would extend the shock absorber beyond the allowable strut
extension in the ground mode.
4.5.4.5 Proper operational procedures shall be defined and followed to ensure vehicle and airplane
stability.
4.6 Vehicle classification
The TLTV model shall be classified according to its intended use, and tested or evaluated accordingly, as
either:
a) category I: pushback only, or
b) category II: maintenance towing only, or
c) category III: both pushback and maintenance.
4.7 Placarding
Limitations and warnings imposed by all conditions shall be placarded in a location readily visible to the tow
vehicle driver, including but not necessarily limited to:
a) classification category defined in clause 4.6;
b) types of aircraft the TLTV is qualified for ( by TLTV setting if applicable );
c) maximum allowable speed;
d) maximum allowable towing angle, etc.
5 Testing requirements
5.1 General
5.1.1 The following tests shall be performed to provide verification that the loads induced by the TLTV do
not exceed the allowable maximum limits, and the operation of the unit in an operational push-back
environment does not result in events potentially jeopardizing aircraft safety.
5.1.2 Dynamic numeric simulation may be used instead of part of the specified tests, unless prohibited by
airframe manufacturer’s documentation, and providing it guarantees at least equivalent
...
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