55-09-01: Magnetic Circuit Breaker
FAA order 55-09-01 is an airworthiness directive published December 4, 1956. The FAA's subject line: Magnetic Circuit Breaker. System: electrical power.
What it applies to as the FAA lists it
- Kind of product
- Aircraft
- Makes
- Aero Spacelines Incorporated
- Models
- 377, 377MG, 377SGT
Dates and paperwork
- Published
- December 4, 1956
- Docket
- Unknown
- Status
- Current
- The FAA's document
- Read the order on the FAA's site
The order itself the regulatory text, as published
Show the full text (740 characters)
55-09-01 BOEING: Applies to all Model 377 aircraft with Hamilton Standard Propellers.
To be accomplished as soon as practicable but not later than June 30, 1955.
Loss of manual r.p.m. control can occur as a result of tripping of the fast-acting magnetic circuit breaker before the slow-acting fuse is blown on a faulted branch. Improved circuit protective coordination and resultant reliability in the manual control function should be provided by replacing the "Manual" 10-ampere magnetic circuit breaker with a 5-ampere thermal type breaker, and replacing the four 5-ampere fuses in the synchronizer unit with 2 ampere Slo-Blo fuses.
(Hamilton Standard Service Bulletin No. 283 dated December 21, 1953, covers this same subject.)
Source: FAA Dynamic Regulatory System, airworthiness directives. The FAA's document is the authority; the register counts are this site's, from the FAA register of November 6, 2026. Connections as data: /graph/directive/55-09-01.json · aircraft systems.