Airworthiness Directives; Turbomeca S.A. Turboshaft Engines
We are superseding airworthiness directive (AD) 2006-23-17 for certain Turbomeca S.A. Turmo IV A and IV C turboshaft engines. AD 2006- 23-17 required repetitive inspections of the centrifugal compressor intake wheel (inducer) blades for cracks and corrosion, replacement of parts that fail inspection, and replacement of the TU 197 standard centrifugal compressor. This AD requires the same inspections, but at revised intervals, adds the replacement of the TU 215 standard centrifugal compressor, and requires replacement of parts that fail inspection. This AD was prompted by a centrifugal compressor inducer blade loss. This AD was also prompted by a Turbomeca S.A. review of the engine service experience and their determination that more frequent borescope inspections (BSIs) are required on engines not modified to the TU 191, TU 197, or TU 224 standard. We are issuing this AD to prevent failure of the centrifugal compressor inducer, which could lead to an uncontained blade release, damage to the engine, and damage to the airplane.
Airworthiness Directives; The Boeing Company Airplanes
We propose to adopt a new airworthiness directive (AD) for The Boeing Company Model 777-200 and -300 series airplanes equipped with Rolls-Royce Model Trent 800 engines. This proposed AD was prompted by reports of damage to the upper bifurcation forward fire seal and seal deflector, and localized damage to the insulation blanket installed just aft of the fire seal. This proposed AD would require installing serviceable thrust reverser (T/R) halves on the left and right engines. We are proposing this AD to prevent a breach in the engine firewall due to a failed upper bifurcation forward fire seal. A breach could delay or prevent the fire detection and suppression system from functioning properly, and could result in an increased risk of a fire, prolonged burning, and breach of the fire zone; and could allow fire to reach unprotected areas of the engine, the strut, and wing after engine shutdown. Also, fan air bypassing the fire seal could cause localized damage to the T/R insulation blanket installed just aft of the fire seal, which could allow limited thermal degradation of the thrust reverser inner wall. This could aggravate existing damage and cause the thrust reverser's inner wall to fail.
Airworthiness Directives; Airbus Airplanes
We propose to supersede Airworthiness Directive (AD) 2003-25- 07 for certain Airbus Model A319 and A320 series airplanes; and AD 2005-13-39 for certain Airbus Model A321 series airplanes. AD 2003-25- 07 currently requires a revision to the airplane flight manual (AFM) and replacement of both elevator aileron computers (ELACs) having L80 standards with new ELACs having L81 standards. AD 2005-13-39 currently requires a revision to the AFM, replacement of existing ELACs with ELACs having either L83 or L91 standards, as applicable; and a concurrent action. Since we issued AD 2003-25-07 and AD 2005-13-39, we have determined that new ELAC standards must be incorporated. The ELAC standards have been upgraded to version L97+, which implements enhanced angle-of-attack (AOA) monitoring to better detect AOA blockage, including multiple AOA blockages. This proposed AD would require replacing existing ELACs with new ELACs having L97+ standards or revising the software in an existing ELAC to the L97+ standards, as applicable, which would terminate the requirements of AD 2003-25-07 and AD 2005-13-39. This proposed AD would also add Airbus Model A318 series airplanes to the applicability. We are proposing this AD to prevent inadvertent activation of the AOA protections. Inadvertent activation of the AOA protections could result in a continuous nose down pitch rate that could result in reduced controllability of the airplane.