70-12-01 GENERAL DYNAMICS: Amdt. 39-1000. Applies to all Model 340 and 440 Series airplanes including those modified in accordance with STC SA4-1100 or STC SA1096WE.
Compliance required as indicated.
Within the next 50 hours time in service, after the effective date of this AD, unless already accomplished within the last 450 hours time in service, visually inspect MLG beam webs P/N 340-1650551-7, -8, -53 and -54 for crack indications in the upper flange radius area by dye penetrant inspection procedures, in accordance with General Dynamics 640-(340D) Service Bulletin No. 57-3, dated April 17, 1970, or later FAA approved revision, or an equivalent inspection procedure approved by the Chief, Aircraft Engineering Division, FAA Western Region.
(a) If no cracks are found, repeat the inspection procedure outlined above at intervals not to exceed 500 hours time in service from the last inspection.
(b) If cracks are found as a result of any of the inspections outlined above, accomplish one of the following before further flight:
(1) If MLG beam web cracking exceeds seven inches total length and/or extends more than two inches forward or aft of the 340-8510109 MLG trunnion fitting, the beam web must be replaced.
(2) If MLG beam web cracking is less than 2.75 inches long and oriented in a wing chordwise direction along the web flange bend radius, either:
(i) Stop drill the crack in accordance with Section 2(B)(3) of S.B. 57-3 or an equivalent rework approved by the Chief, Aircraft Engineering Division, FAA Western Region, and reinspect for further crack propagation at intervals not to exceed 50 hours time in service until the beam is reinforced per (3) below or replaced per (1) above, or
(ii) Replace the beam web.
(3) If cracks are between 2.75 inches and 7.00 inches in length and do not extend more than two inches forward or aft of the 340-8510109 MLG trunnion fitting, either replace the beam web or stop drill and reinforce the beam web per Section 2(B)(4) of S.B. 57-3 or an equivalent rework approved by the Chief, Aircraft
Engineering Division, FAA Western Region. If the beam web is stop drilled and reinforced, it must be reinspected for further crack propagation at intervals not to exceed 500 hours time in service or until the beam web is replaced.
(c) Cracks propagating beyond a stop drill hole may be restop drilled providing the crack length remains within the limits outlined above.
(d) Normal inspection intervals may be resumed when the beam web is replaced.
This amendment becomes effective June 4, 1970.