Service Difficulty Advisory
5 June 2000
Aviadesign STC SA4013WE (Beech 99, King Air, Queen Air & Swearingen SA26)
Main Landing Gear Collapse
Following an incident resulting in a gear collapse on a Beech A100 equipped with Aviadesign Hydraulic Gear Installation, STC SA 4013WE, Transport Canada has concerns that certain characteristics of this STC and the subsequent changes to the Aircraft Flight Manual may have safety implications that other operators of aircraft equipped with this STC should be made aware of.
During routine flight training, repeated cycling of the gear, coupled with a partially depleted landing gear hydraulic accumulator, led to the overheating of the landing gear hydraulic system circuit breaker, causing it to trip. This led to an unsuccessful emergency gear extension.
A depleted nitrogen charge in the landing gear hydraulic accumulator will cause the landing gear hydraulic pump electric motor to cycle excessively and may lead to the overheating of the circuit breaker, causing it to trip. The STC holder recommends inspection of the nitrogen charge every 1000 hours of aircraft operation or at major inspection (Aviadesign Maintenance Manual M-8101). It is strongly recommended that this inspection interval be decreased to 200 hours or less.
Transport Canada also reminds operators with a mixed fleet of similar aircraft, some incorporating this modification to the landing gear system and some not, to ensure that flight crews are fully cognizant of the different procedures amongst the types and understand changes to standard and emergency operating procedures (ref. CARs 705.138 (1) and 604.83).
For further information, contact a Transport Canada Centre, or Mr. Paul Jones, Continuing Airworthiness, Ottawa, telephone (613) 952-4431, facsimile (613) 996-9178 or e-mail firstname.lastname@example.org.
For Director, National Aircraft Certification
Chief, Continuing Airworthiness
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