July 25, 2011
Transport Canada issued an emergency airworthiness directive regarding wing to fuselage attachment joints on DHC-8-400 aircraft models.
Transport Canada reports that there have been three in-service reports of cracked barrel nuts found at the front spar locations of the wing to fuselage attachment joints. Additionally, three operators have reported finding a loose washer in the barrel nut assembly. Failure of the barrel nuts could compromise the structural integrity of the wing to fuselage attachments.
Preliminary investigation determined that these cracks are due to hydrogen embrittlement.
The AD mandates an initial and repetitive detailed inspection of the barrel nuts. The AD applies to all DHC-8 aeroplane models 400, 401 and 402, serial numbers 4001 and subsequent that have accumulated 1900 or more total hours air time or 12 months or more in service since new
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.
November 11, 2010
The European Aviation Safety Agency (EASA) issued an Emergency Airworthiness Directive (AD) for Rolls Royce RB211 Trent 900 series engines following a recent incident involving such an engine on a Qantas A380.
The incident happened on November 4, 2010 when engine nr 2. on a Qantas Airbus A380, VH-OQA, suffered an uncontained failure shortly after takeoff from Singapore.
Analysis of the preliminary elements from the incident investigation shows that an oil fire in the HP/IP structure cavity may have caused the failure of the Intermediate Pressure Turbine (IPT) Disc.
This condition, if not detected, could ultimately result in uncontained engine failure potentially leading to damage to the aeroplane and hazards to persons or property on the ground.
For these reasons and pending conclusion of the incident investigation, the AD requires repetitive inspections of the Low Pressure Turbine (LPT) stage 1 blades and case drain, HP/IP structure air buffer cavity and oil service tubes in order to detect any abnormal oil leakage, and if any discrepancy is found, to prohibit further engine operation.