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COMMERCIAL AND BUSINESS
AVIATION ADVISORY CIRCULAR
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Mobile Aircraft Passenger Stands
PURPOSE
This Commercial and Business Aviation Advisory Circular (CBAAC) is
intended to inform air operators of hazards associated with the use of mobile aircraft
passenger stands and to remind all air operators of their responsibilties regarding
the safe movement of passengers to and from the aircraft.
REFERENCES
- Paragraphs 703.38(1)(a), 704.33(1)(a) and 705.40(1)(a) of the Canadian Aviation
Regulations (CARs).
- Subsections 723.38(1), 724.33(1) and 725.40(1) of the Commercial Air Service
Standards (CASS).
- Transportation Safety Board (TSB) Aviation Occurrence Report A99A0046.
BACKGROUND
On March 31, 1999, a B767 aircraft arrived in St. Johns, Newfoundland,
from London, England. The aircraft was marshalled to a gate on the open ramp and a
passenger stand was positioned at the main passenger door of the aircraft. Two
employees ascended the stairs to open the aircraft door and position the side gates
of the passenger stand. After approximately 10 to 12 passengers had exited the
aircraft, a flight attendant carrying an infant in a car seat deplaned. When the
flight attendant stepped on the passenger stand, he noticed that it was descending
slowly away from the aircraft. As he turned to tell the in-charge flight attendant,
the infants five-year old brother stepped out and fell between the aircraft and
the passenger stand to the apron below. The child suffered a broken arm and
lacerations to the head in the fall.
The passenger stand (Trailbec BMH series unit No.15) used for the deplaning
is designed for use with various aircraft and at different door sill heights. The
stair height is adjusted by means of a moveable upper stair portion which is raised
and lowered by a hydraulic cylinder. The upper stair portion is held in the raised
position by a mechanical pawl and dog locking system.
Following the occurrence, the Transportation Safety Board (TSB) conducted an
investigation which, together with subsequent tests, revealed that the pawls would
fail to engage or only partially engage. Where the pawl partially engaged the dog,
the upper stairs remained in place for a short period, then, as the pawl slipped off
the dog, the stair descended. In tests where the pawl failed to engage the dog, the
stairs began to descend immediately.
The locking mechanism used to hold the upper stairs in position is a fairly simple
mechanical device. The pawl that prevents the stairs from descending is held in place
against the dog rail by a spring and released by energizing a solenoid. In this
occurrence, the pawl had only partially engaged the dog rail and, after several
passengers had travelled over the stairs, it slipped off, allowing the stairs to
descend away from the aircraft.
The company had procedures in place whereby periodic service checks and periodic
operational/safety checks were to be carried out on all ground support equipment to
ensure proper mechanical functioning. However, these procedures were not being
followed and the passenger stand was overdue for a service check.
There was no policy in place requiring the passenger stand operator to do a close
visual inspection of the locking mechanism to ensure full engagement. Other passenger
stand operators reported that they would take only a cursory look at the locking
mechanism when leaving the vehicle. Any visual inspection would have been impeded
because the pawl, the dog rail and the background were all painted the same dark
colour and, on this particular vehicle, a support brace impeded the operators
view.
CONCLUSION
Air operators are reminded of the regulatory requirements to ensure the safe
movement of passengers to and from the aircraft. In addition, air operators using
mobile aircraft passenger stands are urged to ensure that their operational and
safety checks are adequate to confirm equipment serviceability and that their training
and operational procedures are reviewed to ensure that personnel are correctly trained
in the use of the equipment and associated hazards.
M.R. Preuss
Director
Commercial & Business Aviation
Commercial & Business Aviation Advisory
Circulars (CBAAC) are intended to provide information and guidance regarding
operational matters. A CBAAC may describe an acceptable, but not the only,
means of demonstrating compliance with existing regulations. CBAACs in and of
themselves do not change, create any additional, authorize changes in, or
permit deviations from regulatory requirements. |
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