AD 88-17-04

88-17-04 SCHWEIZER AIRCRAFT CORPORATION (MCDONNELL DOUGLAS HELICOPTER COMPANY, HUGHES HELICOPTERS, INC).: Amendment 39-5975. Applies to helicopter Models 269A, TH-55A (all S/N's operated in civil use), 269A-1, 269B, and 269C, certificated in any category. (Docket No. 88-ASW-26)

Compliance is required as indicated, unless already accomplished.

To prevent possible loss of the tail boom support strut and tail boom which could result in loss of the helicopter, accomplish the following:

(a) Within the next 25 hours' time in service after the effective date of this AD, on Model 269C helicopters with S/N's 1166 through 1289, inspect aft cluster fittings (P/N's 269A2234-3 and 269A2235-3) for cracks and surface defects in accordance with the procedures section of Schweizer Service Information Notice (SIN) No. N-220, dated January 29, 1988.

Note: SIN No. 220 provides repair procedures and limits for surface defects.

(b) Within the next 25 hours' time in service after the effective date of this AD conduct the following inspections:

(1) On Models 269A, A-1, B, and TH-55A (all serial numbers) and Model 269C (for all S/N's prior to 1262) conduct a dimensional inspection of the aft cluster fittings (P/N's 269A2234, 269A2235, 269A2234-3, and 269A2235-3) in accordance with Part 1 of Schweizer SIN No. N-217, dated January 29, 1988.

(2) On Model 269C helicopters (S/N's 1262 through 1289) and all other helicopters identified in paragraph (b)(1) as having aft cluster fittings, P/N's 269A2234-3 and 269A2235-3, with fittings purchased from Schweizer Aircraft Corporation between May 1, 1986 and October 22, 1987--

(i) Inspect the fittings for cracks using visual and dye penetrant methods in accordance with Parts II and IV of Schweizer SIN No. N-221, dated January 29, 1988; and

(ii) Remove a sample piece from uncracked fittings and return to Schweizer Aircraft Corporation for laboratory analysis in accordance with Part III of Schweizer SIN No. 221, dated January 29, 1988.

(c) Repeat the inspections of paragraph (b)(2)(i) at the following intervals until the P/N 269A2234-3 and P/N 269A2235-3 fittings are determined to meet the Schweizer process specification or until the aft cluster fittings are replaced with parts which do meet the specifications:

(1) Conduct visual inspections in accordance with Part IV of Schweizer SIN No. N-221, dated January 29, 1988, prior to the first flight of each day.

(2) Conduct dye penetrant inspections in accordance with Part II of Schweizer SIN No. N-221 dated January 29, 1988, at intervals not to exceed 100 hours' time in service from the previous inspections.

(d) Replace fittings found to be cracked or to have surface defects with serviceable fittings before further flight.

(e) No later than December 31, 1988, replace P/N 269A2234-3 and 269A2235-3 fittings not found to meet the Schweizer process specification.

(f) Within the next 25 hours' time in service after the effective date of this AD, on all Model 269A, TH-55A (all S/N's operated in civil use), 269A-1 and 269B (all S/N's) and Model 269C (S/N's 0004 through 1289) install a "NO STEP" placard in accordance with Part II of Schweizer SIN No. N-217 dated January 29, 1988.

(g) Alternative means of compliance which provide an equivalent level of safety with the requirements of this AD may be used when approved by the Manager, New York Aircraft Certification Office, FAA, New England Region.

(h) Aircraft may be ferried in accordance with the provisions of sections 21.197 and 21.199 to a base where the AD can be accomplished.

The procedure shall be done in accordance with Schweizer SIN Nos. N-217, N-220, N- 221, dated January 29, 1988. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from Schweizer Aircraft Corporation, P.O. Box 147, Elmira-Corning Regional Airport, Elmira, New York 14902. These documents also may be examined at the Office of the Regional Counsel, Federal Aviation Administration, Southwest Region, 4400 Blue Mound Road, Fort Worth, Texas, or at the Office of the Federal Register, 1100 L. Street NW, Room 8401, Washington, D.C.

This amendment, 39-5975, becomes effective on August 19, 1988.