BS ISO 9667:2016 pdf download – Aircraft ground support equipment — Tow bars
A given tow bar type may be used on several aircraft types within the same ISO 8267-1 or ISO 8267-2, as appropriate, weight category, provided — their nose landing gear towing interface meets the ISO 8267-1 or ISO 8267-2 requirements for that category, and — the protective provisions are chosen to meet or exceed the minimum requirement for each aircraft. 4 Tow bar general requirements As a safety feature the tow bar (body or head holding section or retaining feature) shall be designed to sustain at least 150 % of the protective device(s) functioning point or as otherwise specified by the customer. The tow bar, when unladen, shall be both towable and stable at speeds up to 25 km/h (15 mph). The maximum towing speed shall be suitably placarded. For use in the EU and EFTA, the tow bar shall, in addition, meet the Health and Safety requirements contained in EN 12312-7:2005, 5.9.
5 Aircraft connection
5.1 Dimension of tow bar connection to aircraft The standard configuration of the tow bar connection to the aircraft shall be compatible with the horizontal pin of the aircraft tow bar attachment fitting as specified in ISO 8267 (all parts).
NOTE Several common aircraft types designed prior to publication of ISO 8267 (all parts) still use non- standard nose gear tow bar attachment fittings. Refer to the aircraft type manufacturer’s documentation for interface requirements.
5.2 Aircraft interface requirements The design of the tow bar aircraft connection device that clamps to the horizontal cylindrical pin of the aircraft — shall grip the pin uniformly over 96 % to 98 % of its length,
— shall be designed to eliminate inadvertent disengagement of the tow bar during towing or pushing operations, — shall be designed to provide adequate clearance during engagement and disengagement of the tow bar from the aircraft connection [allowable space envelope for clearance is specified in ISO 8267 (all parts)], and
— should be adjustable to provide pressure on the pin when locked. NOTE Several common aircraft types designed prior to publication of ISO 8267 (all parts) still use non- standard nose gear tow bar attachment fittings. Refer to the aircraft type manufacturer’s Aircraft Characteristics for Airport Planning Manual for interface requirements. 5.3 Aircraft protective provisions 5.3.1 General requirements The tow bar should be so constructed as to prevent any item from becoming a Foreign Object Damage (FOD) hazard, e.g. broken parts of the shear pin and any bushes always remain captive to prevent aircraft engine ingress.
The tow bar shall incorporate a device or devices, such as for example shear pins (typically two, respectively for push/pull and torsion protection), to protect the aircraft from damage due to towing which shall
— relieve fore/aft and torsional towing forces applied to the aircraft nose gear through the tow bar which exceed the maximum force recommendations of the aircraft manufacturer by means of a shock absorbing device that is designed to function at values below tow bar design values,
— have an energy-absorbing device in order to limit loads induced in the landing gear that shall be designed to function at values beyond tow bar design values,
—simultaneously alert the tow tractor operator, audibly, visually or both, that a device has been actuated,
— be replaceable or repairable with a minimum of effort, and
— transfer overload to a retaining feature preventing separation and therefore loss of control of the aircraft from the towing vehicle. The retaining feature shall allow free rotation on ±90° about aircraft centreline at the retaining fastener. The retaining feature should be designed so that the towing forces do not exceed the aircraft type manufacturer’s maximum force recommendations. See Figure 2 example.
5.3.2 Shear pins If shear pins are used as a protective device, they shall — discourage hazardous replacement and encourage the exclusive use of manufacturer’s original parts and be clearly identified for their specific usage,
— shear at or below the nominal force specified by the aircraft manufacturer(s), — have a functioning point within a relative tolerance of (+0/-10 %), and
— have a specific predetermined shear plane, whether provided with or without hardened bushings (see Figure 2).