70-21-05 HAWKER SIDDELEY AVIATION, LIMITED: Amendment 39-1090. Applies to deHavilland Model DH.114 "Heron" airplanes.
To prevent failure of the flap datum hinge assemblies, unless already accomplished, accomplish the following within the next 3,000 hours' time in service after the effective date of this AD, or by March 31, 1971, whichever occurs first:
(a) Inspect the wall thickness of the bearing housing recess of both the right wing and left wing flap datum hinge links in accordance with Hawker Siddeley Aviation, Limited, Technical News Sheet Heron (114) No. CF.14 Issue 1, June 15, 1970, or later ARB-approved issue or an FAA-approved equivalent. If the wall thickness is found to be less than 0.17 inches, replace the flap datum hinge link with a serviceable link of Modification 837 standard.
(b) Incorporate Modification 837 by replacing the flap datum hinge assemblies P/N 14WF.16A(R.H.) and P/N 4WF.15A(L.H.) with assemblies P/N 14WF.456A(R.H.) and P/N 14WF.455A(L.H.)in accordance with Hawker Siddeley Aviation, Limited, Modification News Sheet, Modification No. Heron 837, dated June 15, 1956, or later ARB-approved issue or an FAA-approved equivalent.
This amendment becomes effective November 5, 1970.