June 30, 2011
The European Aviation Safety Authority (EASA) issued an emergency Airworthiness Directive (AD) effecting specific Airbus A330 and A340-200/-300 aeroplanes. EASA requires reduction of the existing main landing gear (MLG) bogie beam life limits and replacement of each MLG bogie beam that has already exceeded the new limit.
During ground load test cycles on an A340-600 aeroplane, the MLG bogie beam prematurely fractured.
The results of the investigation identified that this premature fracture was due to high tensile standing stress, resulting from dry fit axle assembly method.
Improvement has been introduced subsequently with a grease fit axle assembly method.
Analysis was performed on other bogie beam with dry fit axles. It has been determined that MLG bogie beams with specific part numbers are more likely to suffer from standing stress generated by dry-fit axles because these bogie beams are stiffer between the axle sockets. These two part numbers are fitted on A330, A340-200 and -300 series aircraft.
Fracture of a MLG bogie beam under high speed could ultimately result in the aeroplane departing the runway, or in the bogie detaching from the aeroplane, or MLG collapse, which could cause structural damage to the aeroplane and injury to the occupants.
January 19, 2011
Transport Canada issued an emergency airworthiness directive, ordering of the DHC-8-400 MLG alternative extension system.
Transport Canada reported that two cases of main landing gear (MLG) alternate extension system (AES) cam mechanism failure were found during line checks.
The cam mechanism operates the cable to open the MLG door and releases the MLG uplock in sequence. In the case where it is necessary to deploy the MLG using the AES, the failure of the MLG AES cam mechanism on one side will lead to an unsafe asymmetrical landing configuration. Preliminary investigation indicates that the cam mechanism failure may have occurred and remained dormant after a previous AES operation. The cam mechanism may not have fully returned to the normal rested position. With the cam mechanism out of normal rested position, normal powered landing gear door operation could introduce sufficient loads to fracture the cam mechanism or rupture the door release cable.
The AD mandates the initial and subsequent inspections for proper operation of the MLG AES cam mechanism on DHC-8-400 Series aircraft, and rectify as necessary.
October 19, 2010
Transport Canada issued an emergency airworthiness directive (EAD CF-2010-36) for several models of the Canadair / Bombardier RegionalJet following main landing gear extension problems.
Transport Canada reports two cases of main landing gear (MLG) failure to fully extend on CRJ aircraft. Preliminary investigation has shown that interference between the MLG door and the MLG fairing seal prevented the MLG door from opening. This directive mandates the inspection and rectification, as required, of the MLG fairing and seal, MLG door, and adjacent structures.
Affected are the following models:
- CL-600-2C10 (CRJ-700 series), serial numbers 10003 and subsequent
- CL-600-2D15 (CRJ-705 series)
- CL-600-2D24 (CRJ-900 series), serial number 15001 and subsequent
The AD does not specify the two occurrences, but one of those was probably an incident that occurred on September 25, 2010 involving an Atlantic Southeast Airlines CRJ-900. The airplane landed on at New York-JFK with the right MLG fully retracted.