AD 93-21-03

93-21-03 SCHWEIZER AIRCRAFT CORPORATION AND HUGHES HELICOPTERS, INC.: Amendment 39-8718. Docket Number 91-ASW-11. Supersedes AD 80-05-05, Amendment 39-3707, Docket Number 80-WE-3-AD.

Applicability: Model 269A, 269A-1, 269B, and TH-55A series helicopters, certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent fatigue failure of the magnesium tailboom center attachment [saddle] fitting (fitting) that could result in loss of the tailboom and subsequent loss of control of the helicopter, accomplish the following:

(a) For each helicopter with a magnesium fitting, part number (P/N) 269A2324 (BSC) or 269A2324-7, with 4,000 or less hours' time-in-service on the effective date of this AD, perform the following in accordance with the 269 Series Basic Handbook of Maintenance Information, as revised by Temporary Revision No. R-42, dated October 8, 1990 (HMI):

(1) Prior to further flight and thereafter at intervals not to exceed 50 hours' time-in-service from the last inspection, visually inspect the magnesium fitting and tailboom assembly for fretting, corrosion, and cracks using a 10-power or higher magnifying glass.

(2) Within the next 25 hours' time-in-service after the effective date of this AD and thereafter at intervals not to exceed 100 hours' time-in-service from the last inspection, inspect the magnesium fitting for cracks using a dye penetrant inspection.

(3) If the magnesium fitting, P/N 269A2324 (BSC) or 269A2324-7, is found unairworthy by the inspections required by this paragraph, before further flight, remove and replace it with an airworthy aluminum fitting, P/N 269A2324-13 (undrilled).

(4) Prior to accumulating 4,100 hours' time-in-service, replace the magnesium fitting, P/N 269A2324 (BSC) or P/N 269A2324-7, with an airworthy aluminum fitting, P/N 269A2324-13 (undrilled).

(b) For each helicopter with a magnesium fitting, P/N 269A2324 (BSC) or P/N 269A2324-7, with more than 4,000 hours' time-in-service on the effective date of the AD, perform the following in accordance with the HMI:

(1) Before the first flight of each day, visually inspect the magnesium fitting and tailboom assembly for fretting, corrosion and cracks using a 10-power or higher magnifying glass.

(2) Prior to further flight after the effective date of this AD and thereafter at an interval not to exceed 50 hours' time-in-service from the last inspection, inspect the magnesium fitting for cracks using a dye penetrant inspection.

(3) If the magnesium fitting, P/N 269A2324 (BSC) or 269A2324-7, is found unairworthy by the inspections required by this paragraph, before further flight, remove and replace it with an airworthy aluminum fitting, P/N 269A2324-13 (undrilled).

(4) Within the next 100 hours' time-in-service, replace the magnesium fitting, P/N 269A2324 (BSC) or 269A2324-7, with an airworthy aluminum fitting, P/N 269A2324-13 (undrilled).

(c) Installation of an aluminum fitting, P/N 269A2324-13 (undrilled), constitutes terminating action for the requirements of this AD.

NOTE: Schweizer Aircraft Corporation Service Bulletin B-238.1, dated November 7, 1991, pertains to this AD.

(d) An alternative method of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, New York Aircraft Certification Office, 181 S. Franklin Avenue, Room 202, Valley Stream, New York 11581-1145. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, New York Aircraft Certification Office.

NOTE: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Manager, New York Aircraft Certification Office.

(e) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the helicopter to a location where the requirements of this AD can be accomplished.

(f) This amendment becomes effective December 17, 1993.