69-15-08 VICKERS VISCOUNT: Amdt. 39-805. Applies to Viscount Models 744, 745D, and 810 Series Airplanes.
Compliance required as indicated unless already accomplished.
To prevent fatigue failure of the outer wing spar lower boom accomplish the following:
(a) For Model 744 Series Airplanes, replace the outer wing spar lower booms as follows:
(1) For spar booms that have accumulated less than 70 percent of the approved retirement life, as specified in the last amendment to the applicable Viscount Overhaul Manual, Chapter 5, Overhaul Schedule Section dated before May 15, 1969, replace the outer wing spar lower booms with new booms of the same part number before they accumulate 70 percent of that approved retirement life or before July 31, 1969, whichever occurs later.
(2) For spar booms that have accumulated 70 percent or more of the approved retirement life, as specified in the last amendment to the applicable Viscount Overhaul Manual, Chapter 5, Overhaul Schedule Section dated before May 15, 1969, replace the outer wing spar lower booms with new booms of the same part number before they accumulate 100 percent of that approved retirement life or before July 31, 1969, whichever occurs first.
(b) For Models 745D and 810 Series Airplanes, replace the outer wing spar lower booms as follows:
(1) For spar booms that have accumulated less than 90 percent of the approved retirement life, as specified in the last amendment to the applicable Viscount Instruction Manual 745D Series or Aircraft Manual 810 Series, Chapter 3, Overhaul Schedule Section dated before May 15, 1969, replace the outer wing spar lower booms with new booms of the same part number before they accumulate 90 percent of that approved retirement life or before October 31, 1969, whichever occurs later.
(2) For spar booms that have accumulated 90 percent or more of the approved retirement life, as specified in the last amendment to the applicable Viscount Instruction Manual745D Series or Aircraft Manual 810 Series, Chapter 3, Overhaul Schedule Section dated before May 15, 1969, replace the outer wing spar lower booms with new booms of the same part number before they accumulate 100 percent of that approved retirement life or before October 31, 1969, whichever occurs first.
(c) All new outer wing spar booms that are installed in accordance with the requirements of paragraphs (a) and (b) of this AD must be replaced before the accumulation of the revised retirement life specified in the latest amendment to the applicable Viscount Overhaul Schedule, dated after May 15, 1969, or an FAA approved equivalent.
(d) For the purpose of complying with this AD, subject to acceptance by the assigned FAA maintenance inspector, the number of landings to be used in determining the retirement life of the outer wing spar lower booms may be determined by dividing each aircraft's hours' time in service by the operator's fleet average time from takeoff to landing forthe aircraft type.
This amendment becomes effective July 27, 1969.