Federal Aviation
Administration

MMEL Policy Letter 13, Revision 1

Date:

August 15, 1997

To:

All Region Flight Standards Division Managers
All Aircraft Evaluation Group Managers

From:

Manager, Air Transportation Division, AFS-200

Reply to Attn of:

Manager, Technical Programs Branch, AFS-260

SUBJECT:

Oil Temperature and Pressure Instrument MEL Policy

MMEL CODE:

79 (ENGINE OIL)

REFERENCE:

PL-13 (Item 3), Original, dated February 23, 1984

PURPOSE:

The following guidance is to clarify the agency policy on Oil Temperature and Pressure Indications.

DISCUSSION:

 

Revision 1 contains reformatting, but the policy is unchanged.

This Policy Letter only addresses the subject of oil temperature and pressure. Oil temperature and pressure instruments are required by Federal Aviation Regulations (FAR Sections 23.1305 and 25.1305.)  These instruments provide an indication of the engine's condition and information on certain engine limitations.

POLICY:  

Oil pressure and oil temperature indications are not permitted in MMEL's for Part 121 operations unless other approved means of monitoring these parameters, such as self-monitoring video displays, are provided by the aircraft manufacturer. Because of the unique characteristics of these state-of-the-art installations, they must be evaluated on an individual basis.

 

FAR 135.179 does not permit either type of instrument to be inoperative; therefore, these instruments are not to be included in the MMEL for Part 135 operators unless redundant units are installed and appropriate operating limitations specified.

 

Each Flight Operations Evaluation Board (FOEB) Chairman should apply this Policy to affected MMELs through the normal FOEB process.

 

Manager,

Air Transportation Division, AFS-200

 

PL-13, Rev 1 reformatted 02/04/2010 with no change in content.