69-06-05 FAIRCHILD-HILLER: Amdt. 39-737. Applies to F-27 and FH-227 Type Airplanes Incorporating Lear Siegler (Jack & Heintz) Inverters P/N F35-5 or P/N F45-10 or P/N 40045-000 with Solid State Regulators Lear Siegler Kit P/N 52-000054 (Regulator P/N 51502-000), or Kit P/N 52-000059 (Regulator P/N 51502-001), or Kit P/N 52-000068 (Regulator P/N 51502-00M), or Bendix Type 4B39 Series Regulators.
Compliance required within the next 1200 hours time in service after the effective date of this AD unless already accomplished.
To prevent hazards associated with an inverter overvoltage condition causing the burnout or erratic operation of required instruments, accomplish the following:
(a) Install a.c. overvoltage protection in the electrical output of the above inverter(s) which utilize Lear Siegler solid state regulators, P/N 51502-000, or P/N 51502-001, or P/N 51502-00M, in accordance with Lear Siegler Service Bulletin No. 148-1 dated February 7, 1969, or F-27 aircraftand FH-227 aircraft or later FAA approved revision approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region, or equivalent installation approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region.
(b) Install a.c. overvoltage protection in the electrical output of the above inverter(s) which utilize Bendix 4B39 Series regulators in accordance with Bendix Service Bulletin No. R220 dated November 15, 1968, or later FAA-approved revision approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region, or equivalent installation, approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region.
(c) Upon request with substantiating data, submitted through an FAA maintenance inspector, the compliance time specified in this AD may be increased by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region.
This amendment is effective April 15, 1969.