# AD 76-21-06: Loss of Engine Oil

- Type: Airworthiness directive
- Status: Current
- Products: Cessna 172M, 172N, 177B and 177RG
- Effective: October 26, 1976
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-2750
- Registered aircraft: 8,342 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/35DF0D5ECD08E18E86256A340066DFC6.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/76-21-06

## The airworthiness directive

76-21-06 CESSNA: Amendment 39-2750. Applies to Models 172M (Serial Numbers 17266981 thru 17267584); 172N (Serial Numbers 17267585 thru 67610, 612 thru 621, 623 thru 626, 628 thru 634, 636, 638 thru 648, 651 thru 655, 657, 658, 660 thru 666, 669, 670, 673 thru 679, 681, 682, 684 thru 687, 689, 691 thru 698, 700, 701, 703 thru 706, 708 thru 713, 715, 718, 722 thru 724, 727 thru 729, 732, 736, 738, 739, 74l thru 744, 746 thru 749, 752, 754, 756, 757, 759, 760, 763, 764, 770, 772, 776, 785, 791 and 800); 177B (Serial Numbers 17702450 thru 17702536, 17702538 thru 17702544); and 177RG (Serial Numbers 177RG0875 thru 177RG0990, 177RG0992 thru 177RG0995, 0997 thru 1000, 1002 and 1004) airplanes.

Compliance: Required as indicated, unless already accomplished.

To prevent loss of engine oil, accomplish the following:

A) Before next flight of the affected airplanes, remove the lower engine cowl and visually inspect the engine oil cooler fluid fitting side to determine whetherit is a Model 8406J (S/N 101 thru 1500) or Model 10599A (S/N 101 thru 700).

1. If the oil cooler is not of the model and serial number listed above, make an entry in the aircraft maintenance records indicating that this AD has been accomplished and the airplane may be returned to service.

2. If the oil cooler is of a model and serial number listed above, prior to further flight, replace this cooler with a serviceable oil cooler not of the above model and serial numbers.

B. The inspection and maintenance record entry required by Paragraph A(l) may be accomplished by holder of a pilot's certificate issued under Part 61 of the Federal Aviation Regulations on any aircraft owned or operated by him.

C. Any equivalent method of compliance with this AD must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region.

Cessna Service Letter SE76-17 pertains to this subject.

NOTE: A ferry permit to accomplish a needed oil cooler replacementmay be issued under the provisions of FAR 21.197 by FAA District Offices, with appropriate limitations, in coordination with the Chief, Engineering and Manufacturing Branch, FAA. Central Region.

This amendment becomes effective October 26, 1976, to all persons except those to whom it was made effective earlier by air mail letters issued September 21, 1976, and October 1, 1976, respectively.

## Affected data sheets (3) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 3A12](https://openairdocs.org/tcds/3A12): Textron Aviation Inc.; names 2 of 18 models: 172M, 172N
- [TCDS A13CE](https://openairdocs.org/tcds/A13CE): Textron Aviation Inc.; names 1 of 3 models: 177B
- [TCDS A20CE](https://openairdocs.org/tcds/A20CE): Textron Aviation Inc.; names 1 of 1 models: 177RG

## 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: 8,342 (8,342 by airframe model, 0 by engine model)
- Makers: Cessna 8,342

Models with the most aircraft:

- [Cessna 172M](https://openairdocs.org/model/cessna-172m): 3,573 aircraft (airframe model)
- [Cessna 172N](https://openairdocs.org/model/cessna-172n): 3,138 aircraft (airframe model)
- [Cessna 177B](https://openairdocs.org/model/cessna-177b): 843 aircraft (airframe model)
- [Cessna 177RG](https://openairdocs.org/model/cessna-177rg): 788 aircraft (airframe model)

All 5 models: https://openairdocs.org/ad/76-21-06/models.md
Every aircraft: https://openairdocs.org/ad/76-21-06/aircraft.md

Its text cites no advisory circulars or STCs.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.