AD 47-16-01

47-16-01 DOUGLAS: (Was Mandatory Note 16 AD-762-7.) Applies to C-54 and DC-4 Aircraft.

To be complied with not later than September 1, 1947.

A. In those aircraft having the ammeter shunts in the positive generator leads, install two circuit breakers or circuit breaker switches in each nacelle junction box and reconnect each ammeter lead through one of these circuit breakers. Any type or variety of 10-ampere circuit break may be used, with the exception of the automatic-reset type.

B. Install a circuit breaker or circuit breaker switch in the main junction box and connect in series with the voltmeter circuit wire PJ-34 at the (d.c.) buss. Any type or variety of 10-ampere circuit breaker may be used, with the exception of the automatic-reset type. The nonoverride variety of circuit breaker is preferable.

C. Install for Heinemann type AM 1614-15-28-2 or equivalent, 15-ampere circuit breaker switches or circuit breakers, at the regulator location, in the leads to the B terminal of the voltage regulators; wires PA-530, PA-531, PA-730, and PA-731. The usual thermal circuit breaker or fuse does not provide sufficient protection to meet the peculiar requirements of a protective device for a generator field circuit application.

Additional information on the foregoing changes are described by Douglas Drawing No. 4350951 entitled "Rework of Generator Field Lead and Volt-Ammeter Lead Circuit Protection". A Douglas Aircraft Service Bulletin on this subject is also being issued.