Airworthiness Directive · Amendment 39-15871 · General Electric Company CF34-1A, -3A, -3A1, -3A2, -3B, and -3B1 Turbofan Engines
General Electric Company CF34-1A, -3A, -3A1, -3A2, -3B, and -3B1 Turbofan Engines
This AD applies to General Electric Company (GE) CF34-1A, -3A, -3A1, -3A2, -3B, and -3B1 turbofan engines, with high-pressure (HP) rotor 4-step air balance piston stationary seals (4-step seals), part numbers (P/Ns) 4923T54G01, 6019T90G03, 6037T99G01, 6037T99G02, and 6037T99G03, installed. These engines are installed on, but not limited to, Bombardier, Inc. airplane models CL-600-2A12, -2B16, and -2B19.
The FAA is adopting a new airworthiness directive (AD) for General Electric Company (GE) CF34-1A, -3A, -3A1, -3A2, -3B, and -3B1 turbofan engines with high-pressure (HP) rotor 4-step air balance piston stationary seals (4-step seals), part numbers (P/Ns) 4923T54G01, 6019T90G03, 6037T99G01, 6037T99G02, and 6037T99G03, installed. This AD requires removing the 4-step seals and incorporating an 8-step seal at the next piece-part exposure. This AD results from the investigation of an airplane accident. Both engines experienced high-altitude flameout. Rotation of the HP rotors was not maintained during descent and the engines could not be restarted. We are issuing this AD to prevent the inability to restart both engines after flameout due to excessive friction of the 4-step seal, which could result in subsequent forced landing of the airplane.
You are responsible for having the actions required by this AD performed at the next piece-part exposure after the effective date of this AD, unless the actions have already been done.
(f) Remove the 4-step seals, P/Ns 4923T54G01, 6019T90G03, 6037T99G01, 6037T99G02, and 6037T99G03.
(g) Incorporate an 8-step seal, either by modifying the existing 4-step seal to an 8-step seal, or by replacing it with an 8-step seal.
(h) Information on modifying the seal and part number configuration charts, can be found in GE Service Bulletin (SB) No. CF34-AL S/B 72-0238, dated July 27, 2007 (CL-600-2B19), and SB No. CF34-BJ S/B 72-0217, dated July 27, 2007 (CL-600-2A12 and CL-600-2B16).
(i) For the purposes of this AD, piece-part exposure means when the 4-step seal is removed from the engine or when the combustion liner is removed.
