AD 81-10-02

81-10-02 HILLER AVIATION: Amendment 39-4103. Applies to all Models FH 1100 Series Helicopter, certified in all categories, Serial Nos. 001 through 254.

Compliance required as indicated, unless already accomplished.

To prevent the upper controls support column from contacting and damaging the main rotor mast accomplish the following:

(a) Within the next ten (10) calendar days from the effective date of this AD

(1) Accomplish a one time visual inspection of the support column P/N 24-30208 to determine whether or not the base flange P/N 24-30210 is undersized. Inspection is to be performed in accordance with Hiller Service Bulletin SB 30-9, Part 2, Subpart B, dated April 3, 1981.

(2) If the inspection (a) (1) determines that the flange thickness is in accordance with type design (specifically 0.090 0.010 inches), no further AD action is required.

(b) After inspection of paragraph (a) (1) and a determination that the flange thickness is undersized, prior to further flight

(1) Replace the support column P/N 24-30208 with a like serviceable part which is in compliance with type design; and

(2) Inspect the main rotor mast for damage (nicks, scratches or dents) at the top of the support column location, approximately 12.375 inches from top of upper housing of transmission. Replace each damaged main rotor mast with a like serviceable part.

NOTE: The main rotor mast cannot be inspected until the upper controls and support column are disassembled.

NOTE: Hiller kits P/N SBK-FH-1100-23-2 and spares stock may contain undersize flight control system support columns.

(c) Verify that any replacement support column is in compliance with type design as noted in paragraph (a) (2) prior to return to service.

Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate helicopters to a base for the accomplishment of inspections and maintenance required by this AD.

Alternative inspections, modifications or other actions which provide an equivalent level of safety may be used when approved by the Chief, Engineering and Manufacturing Branch, FAA Western Region.

Manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 553(a)(1). All persons affected by this directive, who have not already received these documents from the manufacturer, may obtain copies upon request to Hiller Aviation, 2075 West Scranton Avenue, Porterville, California 93275. These documents may also be examined at FAA Western Region Office, Room 6W14, 15000 Aviation Boulevard, Hawthorne, California 92061; and at FAA Headquarters, 800 Independence Avenue, S.W., Washington, D.C. 20591.

A historical file on this AD, which includes the incorporated material in full, is maintained by the FAA at its headquarters in Washington, D.C. and at FAA Western Region Office.

This amendment becomes effective May 11, 1981.