AD 77-07-10

77-07-10 BRITTEN NORMAN, LTD.: Amendment 39-2869. Applies to Models BN-2A Islander and BN-2A Mk III Trislander airplanes, all series, certificated in all categories, except those airplanes incorporating Britten Norman Modification NB/M878.

Compliance is required as indicated, unless already accomplished.

To detect internal corrosion and prevent possible failure of the aileron mass balance support arm, accomplish the following:

(a) For ailerons modified in accordance with Britten-Norman, Ltd. Modification NB/M/336, within the next 25 hours time in service after the effective date of this AD or prior to 3 years since new, whichever occurs later, accomplish the following:

(1) Gain access to and inspect the interior surface of the aileron mass balance support arm in accordance with steps 1 thru 4 of Part 1 and Figure 1 of Britten-Norman, Ltd. Service Bulletin BN-2/SB.98, Issue 1, dated October 27, 1976 (hereinafter S.B. BN- 2/SB.98), or an FAA-approved equivalent.(2) If no corrosion or acceptable corrosion (as defined in Table 1 of Figure 1 of S.B. BN-2/SB.98) is found as a result of the inspection required by paragraph (a)(1) of this AD, clean and protect the interior surface of the support arm and the shank of the bobweight in accordance with subpart (a) of step 5, and reassemble in accordance with steps 6 through 9, of Part 1 of S.B. BN-2/SB.98, or an FAA-approved equivalent.

(3) If marginal corrosion (as defined in Table 2 of Figure 1 of S.B. BN- 2/SB.98) is found as a result of the inspection required by paragraph (a)(1) of this AD, before further flight, clean, protect, and reassemble the support arm, in accordance with paragraph (a)(2) of this AD. Thereafter, within the next 300 hours time in service or 3 months, whichever occurs sooner, replace the support arm with a new part of the same part number or an FAA-approved equivalent, and reassemble in accordance with paragraph (a)(2) of this AD.

(4) If, during the inspection required by paragraph (a)(1) of this AD, corrosion is found beyond acceptable limits (as defined in Table 3 of Figure 1 of S.B. BN- 2/SB.98), before further flight, replace the support arm with a new part of the same part number, or an FAA-approved equivalent, and reassemble in accordance with paragraph (a)(2) of this AD.

(b) For ailerons not modified in accordance with Britten-Norman, Ltd. Modification NB/M/336, within the next 25 hours time in service after the effective date of this AD or prior to 3 years since new, whichever occurs later, accomplish the following:

(1) Gain access to and inspect the interior surface of the mass balance support arm in accordance with steps 1 thru 4 of Part 2 and Figure 2 of S.B. BN-2/SB.98, or an FAA-approved equivalent.

(2) If no corrosion or acceptable corrosion (as defined in Table 1 of Figure 1 of S.B. BN-2/SB.98) is found as the result of the inspection required by paragraph (b)(1) of this AD, clean and protect the interiorsurface of the support arm and the shank of the bobweight in accordance with subpart (a) of Step 5, Part 1, and repair the support arm in accordance with Figure 2 and reassemble in accordance with steps 6 thru 9, of Part 2 of S.B. BN-2/SB.98, or an FAA-approved equivalent.

(3) If marginal corrosion (as defined in Table 2 of Figure 1 of S.B. BN- 2/SB.98) is found as a result of the inspection required by paragraph (b)(1) of this AD, before further flight, clean, protect, repair, and reassemble the support arm and shank of the bobweight in accordance with paragraph (b)(2) of this AD. Thereafter within the next 300 hours time in service or 3 months, whichever occurs sooner, replace the support arm in accordance with the repair and reassembly instructions specified in Part 3 and Figure 3, of S.B. BN-2/SB.98, or an FAA-approved equivalent.

(4) If, during the inspection required by paragraph (b)(1) of this AD, corrosion is found beyond acceptable limits (as defined in Table 3 of Figure 1 of S.B. BN- 2/SB.98), before further flight, replace the support arm in accordance with Part 3 and Figure 3 of S.B. BN-2/SB.98, or an FAA-approved equivalent.

This amendment becomes effective April 18, 1977.