66-29-01 BOEING: Amdt. 39-301 Part 39 Federal Register November 5, 1966. Applies to Model 727 Series Airplanes. \n\n\tCompliance required as indicated. \n\n\tTo prevent loss of the cowl panels in flight, and resulting damage to the aircraft structure, accomplish the following or an equivalent approved by the Chief, Aircraft Engineering Division, FAA Western Region: \n\n\t(a)\tWithin the next 1,500 hours' time in service after the effective date of this AD, unless already accomplished, modify the side engine cowl panel latch assemblies in accordance with Boeing Service Bulletin No. 71-14 or later FAA-approved revision. Replacement of Hartwell Manufacturing Company hook latch spring, P/N 104914-1, with P/N 106054-1 is optional. \n\n\t(b)\tWithin the next 3,000 hours' time in service after the effective date of this AD, unless already accomplished, modify the center engine cowl panel latch frames in accordance with Boeing Service Bulletin No. 71-27 or later FAA-approved revision. \n\n\tThisdirective effective December 5, 1966.