AD 56-18-01

56-18-01 CONVAIR: Applies to All 240 Series Aircraft.

Compliance required as indicated.

Instances of complete electric power system failure have occurred inadvertently upon failure of a single generator or engine. Due to high overloading that may be imposed on the remaining single generator, this generator is subject to failure unless prompt action is taken to reduce electrical loads within the generator's rated capacity. In order to improve electric power system reliability, the following shall be provided on aircraft in which a probable combination of electric utilization loads can exceed the continuous rating of one generator:

1. Generator Inoperative Warning Light (at least one, located for reliable warning), to be installed by April 1, 1957.

2. Monitoring System (add relays and circuitry to automatically disconnect buffet power and one inverter in case of loss or disconnection of one generator, with monitor override switch optional), to be installed by September 1, 1957. The automatic monitoring system is not required if it can be shown that the crew can manually reduce the total utilization load to the rating of one generator within 15 seconds after a generator or engine failure during any flight condition. A longer time interval than 15 seconds may be accepted if substantiated by demonstrations on representative generators which have reached approximately full overhaul time.

(Convair Service Newsletter No. 352 dated June 16, 1956, contains preliminary technical information, including schematic wiring diagrams, relative to this same subject.)

Final reworks must be in accordance with FAA-approved technical data.