Federal Aviation Administration April 6, 2007 – Federal Register Recent Federal Regulation Documents

The FAA is superseding an existing airworthiness directive (AD) for General Electric Company (GE) CF34-1A, -3A, -3A1, -3A2, -3B, and -3B1 turbofan engines. That AD requires a onetime inspection of certain fan disks for electrical arc-out indications, replacing fan disks with electrical arc-out indications, and reducing the life limit of certain fan disks. This AD requires the same reduced life limit of certain fan disks, but requires on-wing inspection of certain fan disks installed on regional jets within 500 flight hours after the effective date of this AD. This AD also requires more enhanced shop-level inspections of all fan disks for electrical arc-out defects. This AD results from a report that in January 2007, a CF34-3B1 turbofan engine experienced an uncontained fan disk failure during flight operation. We are issuing this AD to prevent an uncontained fan disk failure and airplane damage.

We are clarifying information contained in Airworthiness Directive (AD) 2007-06-01, which supersedes AD 62-24-01 and applies to all Raytheon Aircraft Company (RAC) Beech Models 45 (YT-34), A45 (T- 34A, B45), and D45 (T-34B) airplanes. AD 2007-06-01 currently requires you to repetitively inspect, using the eddy current method, the front and rear horizontal stabilizer spars for cracks and replace any cracked stabilizer. We inadvertently left out the language in this AD that required replacement of any horizontal stabilizer spar found cracked prior to further flight although the procedures in the appendix made reference to corrective action. The replacement information was contained in the notice of proposed rulemaking (NPRM). This document adds this information already proposed back into the AD. We are issuing this AD to prevent failure of the front and/or rear horizontal stabilizer spars caused by fatigue cracks. This failure could result in stabilizer separation and loss of control of the airplane.