72-12-05 HAWKER SIDDELEY AVIATION LTD.: Amdt. 39-1458. Applies to Hawker Siddeley deHavilland Model DH-114 "Heron" airplanes which do not have Modification 1161 incorporated on all of the main landing gear and nose landing gear operating jacks.
Compliance required as indicated.
To prevent the possible failure of the main or nose landing gear operating jacks accomplish the following:
(a) Within the next 50 landings after the effective date of this AD, or before accumulating a total of 5,000 landings on a piston, P/N AHO 19742, in an operating jack assembly, whichever occurs later
(1) Replace the affected operating jack assembly with a serviceable jack assembly which has been modified to incorporate piston, P/N ACO 23389, (Modification 1161) in accordance with de Havilland Aircraft Service, Modification News Sheet No. Heron 1161, dated March 17, 1958, or an FAA-approved equivalent, or
(2) Replace the piston in each affected operating jack assembly with a newpiston of the same part number and thereafter continue to replace P/N AHO 19742 pistons at intervals not to exceed 5,000 landings.
(b) Operators who have not kept records of the number of landings on individual pistons, P/N AHO 19742, shall substitute the total number of airplane landings accumulated in lieu thereof.
(de Havilland Aircraft Service, Technical News Sheet, Series: Heron (114) No. S.2 dated March 1, 1959, covers this same subject.)
This amendment is effective upon publication in the Federal Register as to all persons except those persons to whom it was made immediately effective upon receipt of the airmail letter dated April 20, 1972, which contained this amendment.