56-25-04: Flap Symmetry
FAA order 56-25-04 is an airworthiness directive. The FAA's subject line: Flap Symmetry. System: flight controls.
What it applies to as the FAA lists it
- Kind of product
- Aircraft
- Makes
- Lockheed Aircraft Corporation
- Models
- 1049-54, 1049C-55, 149-46, 49-46, 649-79, 649A-79, 749-79, 749A-79
Dates and paperwork
- 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 (758 characters)
56-25-04 LOCKHEED: Applies to All Models 49, 149, 649, 649A, 749, 749A Aircraft; Model 1049 Serial Numbers 4001 Through 4024; Model 1049C Serial Numbers 4501 Through 4520 and 4523 Through 4538.
Compliance required at first block overhaul following receipt of parts or by March 1, 1958, whichever occurs first.
In view of the continuing series of incidents wherein flaps extend on one side of the aircraft out of symmetry with the other side, a means shall be installed which will automatically shut off the hydraulic power to the flap actuating motors whenever an asymmetrical condition exists. One method of accomplishing this means is described in Lockheed Service Bulletin No. 49/SB-794 for the 49/749 Series and No. 1049/SB-2270 for the 1049 Series.
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/56-25-04.json · aircraft systems.