- Models
- DC-7, DC-7B, DC-7C, 1049-54, 1049B-55 (Navy R7V-1), 1049C-55 and 13 more
- Registered aircraft
- 9 matched by model
- Product
- Aircraft · Large airplane
Unofficial copy of the text in the FAA’s Dynamic Regulatory System. The FAA’s own copy is the authoritative one. DRS record last changed May 30, 2024.
Copies of the files this page was built from, with their SHA-256. Retrieved October 18, 2026.
| File | Size | SHA-256 | Original |
|---|---|---|---|
| FAA DRS HTML | 20 KB | 464c74bf…68d9765 | FAA DRS (API key needed) |
On this page
The airworthiness directive
57-03-03 DOUGLAS AND LOCKHEED: Applies to Lockheed Constellation Series and Douglas DC-7 Series Airplanes.
Compliance required by April 1, 1957, for Constellation aircraft and by May 1, 1957, for DC-7 aircraft.
Under certain cold weather operating conditions the perforated paper covering around the Purolator micronic filter elements are subject to accumulation of ice as a result of entrained water crystals in the fuel freezing on this covering. This interferes with proper fuel filtering by causing the fuel to pass through the bypass valve in the filter unit. To make the micronic filter less susceptible to clogging by ice, the perforated paper covering around the filter element is to be removed. Removal of the perforated cover does not affect the filtering characteristics of the filter element. Filter elements without the paper covering are identified as Purolator P/N 30868-3.
Affected TCDS · 4
The type certificate data sheets for the models this AD names, matched by model and maker.
Registered aircraft · 9
Registered aircraft whose airframe or engine model this AD names. Matched by model only, so check each against the AD’s applicability.
| 1946 | 1 |
|---|---|
| 1949 | 1 |
| 1957 | 2 |
| 1958 | 2 |
| 1959 | 1 |
2 with no year recorded