| AD Number | 55-15-06 | Status | Active |
| Effective Date | Not specified | Issue Date | Not specified |
| Docket Number | Unknown | Amendment | N/A |
| Product Type | ["Aircraft"] | Product Subtype | ["Large Airplane"] |
| CFR Part | --- - Part 39 | CFR Section | N/A |
| Citation | This information is not available. | ||
| Manufacturer(s) | Lockheed Aircraft Corporation |
| Model(s) | 1049C-55 1049D-55 1049E-55 149-46 49-46 649-79 649A-79 749-79 749A-79 |
55-15-06 LOCKHEED: Applies to 049, 149 Aircraft, Serial Numbers 1963 Through 1980, 2021 Through 2088; 649-749 Aircraft, Serial Numbers 2503 Through 2590, 2610, 2611, 2614 Through 2618; 1049C Aircraft, Serial Numbers 4501 Through 4548; 1049E Aircraft, Serial Numbers 4549 Through 4555, 4558, 4559, and 4563 Through 4565; 1049D Aircraft, Serial Numbers 4163 Through 4166.
Compliance required by April 1, 1956, for Model 1049 aircraft and October 1, 1956, for Models 049/149 and 649/749 aircraft.
To improve the fire-resistance integrity of the above aircraft, revisions to the system supplying cooling air to the accessory section of the powerplant installation are considered necessary.
For 049-149 aircraft and 649-749 aircraft, the revision consists of installing a shutoff valve in a fireproof duct.
For the 1049C and E aircraft, the revision consists of replacing a section of aluminum duct between the oil cooler scoop, and the existing shutoff valve, with a fireproof duct. This section is in zone 1, and provides a possible zone 1 to zone 2 firepath.
Lockheed Service Bulletins 49/718, for 049/149 aircraft; 1049/2384, for 1049 aircraft; and 49/391A, for 649-749 aircraft, cover these subjects.