76-06-04 HAWKER SIDDELEY AVIATION, LTD: Amendment 39-2553. Applies to Model DH-104 "Dove" airplanes, all series, certificated in all categories.
Compliance is required as indicated.
To prevent the possible failure of engine mounting pick-up brackets, accomplish the following:
(a) Within the next 50 hours' time in service after the effective date of this AD, unless already accomplished within the preceding 250 hours' time in service, inspect the following engine mounting pickup brackets in accordance with paragraph (b) of this AD, and comply with paragraph (c), (d), and (e), as appropriate.
(1) For aircraft that do not incorporate Hawker Siddeley Modification 38, inspect -
(i) Inboard top joint assembly inner brackets, P/N 4 W.3433-4, and outer brackets, P/N 4 W.3435-6; and
(ii) Outboard top joint assembly inner brackets, P/N 4 W.3437-8, and outer brackets, P/N 4 W.3439-40.
(2) For aircraft that incorporate Hawker Siddeley Modification 38, inspect -
(i) Inboard top joint assembly inner brackets, P/N 4 W.4239-40, and outer brackets, P/N 4 w.4241-2; and
(ii) Outboard top joint assembly inner brackets, P/N 4 W.3437-8, and outer brackets, P/N 4 W.3439-40.
(b) Remove the cowling over the oil tank and inspect the engine mounting pick-up brackets specified in paragraph (a)(1) or (a)(2) of this AD, as applicable, for cracks using a dye penetrant method, and comply with paragraph (c) or (d) of this AD, as appropriate.
NOTE. In conducting inspections required by paragraph (b) of this AD particular attention should be given to the top flanged edges of the brackets.
(c) If a crack is found during an inspection required by paragraph (b) of this AD, before further flight, replace the affected bracket with a new bracket of the same part number or an FAA-approved equivalent.
(d) If no crack is found during an inspection required by paragraph (b) of this AD, before further flight, inspect the flange edges of the brackets specified in paragraph (a)(1) or (a)(2), as appropriate, for cut-outs, nicks, rough edges, and similar defects.
(e) If a defect is found during an inspection required by paragraph (d) of this AD, comply with the following, as appropriate:
(1) If the defect can be blended out over a length of at least 0.5 inches along the flange edge, without a material loss in excess of 0.05 inches from the edge of the flange, accomplish the following:
(i) Before further flight, blend out the defect, and
(ii) Thereafter, continue to comply with paragraph (b) of this AD at intervals not to exceed 1200 hours' time in service.
(2) If the defect can be blended out over a length of at least 0.5 inches along the flange edge, with a material loss in excess of 0.05 inches, but not in excess of 0.20 inches, from the edge of the flange, accomplish the following:
(i) Before further flight, blend out the defect, and
(ii) Thereafter, continue to complywith paragraph (b) of this AD at intervals not to exceed 300 hours' time in service.
(3) If the defect cannot be blended out over a length of at least 0.5 inches along the flange edge, or a material loss in excess of 0.20 inches from the edge of the flange would result if the defect were blended out, before further flight, except that the airplane may be flown in accordance with FAR 21.197 and 21.199 to a base where the repair can be performed, replace the affected bracket with a new bracket of the same part number, or an FAA-approved equivalent.
(f) The blending out of defects as required by paragraphs (e)(1)(i) and (e)(2)(i) of this AD must be accomplished in such a manner that all reworked edges are smooth, free of burrs, and reprotected in accordance with FAR 43.13.
NOTE. The Hawker Siddeley Aviation Limited Model DH-104 Maintenance Manual contains instructions for the blending out of defects.
Also Hawker Siddeley Aviation Limited Technical News Sheet CT(104)No. 226, Issue 1, dated October 25, 1971, deals with this subject.
This amendment becomes effective March 29, 1976.