AD 91-05-18 ACTIVE

91-05-18 SCHWEIZER AIRCRAFT CORPORATION (HUGHES HELICOPTERS, INC.): Amendment 39-6857. Docket No. 90-ASW-46.

Applicability: All Model 269C series helicopters, certificated in any category.

Compliance: Required as indicated, unless previously accomplished.

To prevent fatigue failure of the magnesium tailboom center attachment (saddle) fittings which could result in loss of the tailboom of the helicopter, accomplish the following:

(a) For helicopters with a magnesium tailboom center attachment fitting, P/N 269A2324-7, installed with 400 hours' or less total time in service, perform the following in accordance with the 269 Series Basic Handbook of Maintenance Information (HMI), as revised by Temporary Revision No. R-42, dated October 8, 1990 (HMI):

(1) Prior to further flight after the effective date of this AD, and thereafter at intervals not to exceed 50 hours' time in service from the last inspection, inspect the magnesium tailboom center attachment fitting and tailboom visually using a 10-power or higher magnifying glass, in accordance with the HMI.

(2) Within 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 tailboom center attachment fitting using a dye penetrant inspection in accordance with the HMI.

(3) Remove and replace the magnesium tailboom center attachment fitting, P/N 269A2324-7, with an aluminum tailboom center attachment fitting, P/N 269A2324-11 or P/N 269A2324-11T, as prescribed by the HMI prior to attaining 500 hours' total time in service.

(b) For helicopters with magnesium tailboom center attachment fitting, P/N 269A2324-7, installed with more than 400 hours' total time in service, perform the following in accordance with the HMI:

(1) Prior to further flight and thereafter at an interval not to exceed 50 hours' time in service from the last inspection, inspect thetailboom center attachment fitting using a dye penetrant inspection as prescribed in paragraph (a)(2) of this AD.

(2) Before the first flight of each day inspect the tailboom center attachment fitting and tailboom visually using a 10-power or higher magnifying glass as prescribed in paragraph (a)(1) of this AD.

(3) Remove and replace the magnesium tailboom center attachment fitting, P/N 269A2324-7, with an aluminum tailboom center attachment fitting, P/N 269A2324-11 or P/N 269A2324-11T, as prescribed in the HMI, within the next 100 hours time in service after the effective date of this AD.

(c) Remove and replace the magnesium tailboom center attachment fitting, P/N 269A2324-7, with an aluminum tailboom center attachment fitting, P/N 269A2324-11 or P/N 269A2324-11T, before further flight if it is cracked or otherwise unserviceable.

NOTE: Schweizer Service Bulletin B-239, dated October 8, 1990, pertains to this AD. The tailboom assembly service life is 2,100 hours.(d) Aircraft may be ferried in accordance with the provisions of FAR Sections 21.197 and 21.199 to a base where the requirements of this AD can be accomplished.

(e) Alternate inspections, modification, or adjustments of the compliance times, which provide an equivalent level of safety may be used when approved by the Manager, New York Aircraft Certification Office, FAA, 181 South Franklin Avenue, Room 202, Valley Stream, NY 11581.

This amendment (39-6857, AD 91-05-18) becomes effective on March 29, 1991.