# AD 47-27-04: Exhaust Collector Rings

- Type: Airworthiness directive
- Status: Current
- Products: Boeing C54-DC, C54A-DC, C54B-DC, C54D-DC, C54E-DC, C54G-DC and DC-4
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Registered aircraft: 4 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/D3529B62F6C6A73086256833006E0679.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/47-27-04

## The airworthiness directive

47-27-04 DOUGLAS: (Was Mandatory Note 18 of AD-762-7.) Applies to All C-54 and DC-4 Series Airplanes Having Exhaust Collector Rings Made Up of Top Segments P/N 5174842-56 L.H. and 5174529-56 R.H.

To be accomplished not later than the first engine change subsequent to July 15, 1947, but in any event not later than October 15, 1947.

Several reports have been received of cracking failure of the collector ring "Y" outlet assembly due to breathing of the exhaust stack. This induces failure which creates a fire hazard. This type of exhaust collector "Y" is not reinforced with a flange and is shown on page 4, Douglas Service Bulletin No. DC-4 No. 31. To correct this condition weld a scalloped stiffener flange on the exhaust collector aft of the "Y" outlet assembly.

(Douglas Service Bulletin No. DC-4 No. 68 covers this same subject.)

Until this repair is accomplished, inspection for cracks should be made immediately and at periods not to exceed 50 hours of operation.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A-762](https://openairdocs.org/tcds/A-762): The Boeing Company; names 7 of 7 models: C54E-DC, C54G-DC, C54B-DC, DC-4, C54A-DC, C54D-DC, C54-DC

## Registered aircraft it may apply to (OpenAirDocs)

Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment.

- Aircraft: 4 (4 by airframe model, 0 by engine model)
- Makers: Douglas 4

Models with the most aircraft:

- [Douglas C54D-DC](https://openairdocs.org/model/douglas-c54d-dc): 2 aircraft (airframe model)
- [Douglas C54E-DC](https://openairdocs.org/model/douglas-c54e-dc): 1 aircraft (airframe model)
- [Douglas C54G-DC](https://openairdocs.org/model/douglas-c54g-dc): 1 aircraft (airframe model)

All 3 models: https://openairdocs.org/ad/47-27-04/models.md
Every aircraft: https://openairdocs.org/ad/47-27-04/aircraft.md

Its text cites no advisory circulars or STCs.

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