AD 67-33-02

67-33-02 de HAVILLAND AIRCRAFT: Amdt. 39-532, Part 39, Federal Register December 30, 1967. Applies to Type DHC-6 Aircraft.

Due to flutter of the left elevator trim tab, accomplish the following after the effective date of this AD unless already accomplished.

(a) Prior to the next flight, install the following placard in full view of the pilot: "SPEED SHALL NOT EXCEED 125 KNOTS IAS (144 M.P.H. IAS)".

(b) Prior to the next flight, accomplish the following one-time inspections on the left elevator-trim tab assembly:

(1) Remove the bolt between the push rod and the tab operating lever and operate the trim tab control in the cockpit until the screw jack in the elevator is fully retracted. Lower the tab until the bolt can be inserted through the operating arm and the push rod without exerting pressure on the trim tab. If this can be accomplished, reconnect the tab to the push rod. If the holes do not align, adjust the push rod sufficiently to allow assembly withoutexerting pressure on the trim tab.

(2) With the trim tab in the neutral position, assure that the total vertical free play, measured adjacent to the operating lever, does not exceed one-tenth (0.1) inches at the trailing edge of the tab. Comply with this limit prior to further flight.

(c) Before each flight, visually inspect the left elevator trim tab top and bottom skins for diagonal buckling or concavity, other than the manufactured flutes. Trim tabs found to contain diagonal buckles or concavities must be replaced before further flight with a part of the same part number that has been inspected in accordance with this paragraph, or with an equivalent part approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. The repetitive inspection required by this paragraph also applies to replacement parts.

(d) The placard required by (a) may be removed, and the repetitive inspection required by (c) may be discontinued, when a trim tab modification,approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region, is incorporated.

(e) Upon request with substantiating data submitted through an FAA maintenance inspector, the compliance time specified in this AD may be increased by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region.

This amendment effective December 30, 1967, for all persons except those to whom it was made effective immediately by telegram dated December 1, 1967.