Federal Aviation Administration July 25, 2012 – Federal Register Recent Federal Regulation Documents

We propose to supersede an existing airworthiness directive (AD) that applies to all Turbomeca S.A. Arriel 1A, 1A1, 1A2, 1B, 1C, 1C1, 1C2, 1D, 1D1, 1E, 1E2, 1K, 1K1, 1S, and 1S1 turboshaft engines. The existing AD currently requires initial and repetitive visual inspections for erosion caused by dust ingestion and, if necessary, cleaning of the gas generator (module M03). Since we issued that AD, in-service experience has shown that dust inside the gas generator hollow shaft may be found when the axial compressor wheel has less erosion than initially assessed. This proposed AD would require determining the engine history, a one-time visual inspection of the axial compressor for erosion, initial and repetitive cleaning of the gas generator hollow shaft, and replacement of the rear bearing if the amount of dust collected during cleaning exceeds 8 grams. This proposed AD also includes an optional terminating action. We are proposing this AD to prevent an unbalance of the gas generator rotating assembly, which may lead to gas generator rear bearing failure, and uncommanded engine shutdown.

We propose to supersede an existing airworthiness directive (AD) that applies to certain Bombardier, Inc. Model DHC-8-400 series airplanes. The existing AD currently requires a modification to trim the edge of the bumper plate, including performing an inspection for damage or cracks of the bumper plate and base fitting, and replacing any damaged or cracked part. That AD also currently requires, for certain airplanes, reidentifying the bumper plate. Since we issued that AD, we have determined that an operational check must be done after reidentifying the bumper plate to ensure the identified unsafe condition is addressed. This proposed AD would require, for airplanes on which the reidentification is done, an operational check of the alternate extension system of the main landing gear (MLG), and repair if necessary. We are proposing this AD to detect and correct failure of the MLG to extend and lock, which could adversely affect the safe landing of the airplane.