71-08-04 BRITISH AIRCRAFT CORPORATION: Amdt. 39-1191. Applies to Vickers Viscount Models 744, 745D, and 810 series airplanes.
Compliance is required as indicated.
To prevent a hazardous drift in the bus-bar undervoltage sensing unit setting, within the next 1000 hours' time in service after the effective date of this AD or upon installation of the bus- bar undervoltage warning light in accordance with AD 70-02-04, whichever occurs later, incorporate Rotax Modification SP7174 by replacing the transistor T.1 in the Rotax Voltage Sensing Unit Type U.3619 with a new transistor in accordance with Rotax Service Bulletin No. 24- 368 dated 4 May 1970, or later ARB-approved issue or an FAA approved equivalent.
(British Aircraft Corporation Bulletin for Modification No. D3246, 3rd Issue, dated 12 May 1970, and Bulletin for Modification FG.2123, 3rd Issue, dated 12 May 1970 refer to this subject).
This amendment becomes effective May 8, 1971.