Proposed EngineAD / Piper SB 644E

[orca]

Hi All,
I have just been made aware of a proposed engine AD on the Federal Register, dated 09/18/2012, document #2012-22953, that is hinged to Piper recent SB 644E.
The Piper SB is fairly clear as to the inspection/replacement requirements with P/Ns that relieves the repetitive replacement requirement of exhaust coupling clamp.
The AD is not P/N specific and has a proposed mandatory 1000hr replacement requirement with no relief. I have no problem with the repetitive inspection requirements but wonder about the repetitive replacement requirements, is this for all clamps?
Has anyone had dealings with either and do I understand the proposed AD correctly?
Cheers, Harald (Orca)

[jmmiller]

Have to agree with you Piper SB 644E clearly states that if you replace the V-Band Clamp with Piper P/N 557-369, the repetitive inspection is no longer required.

We have been requiring a visual inspection per Piper MSB 644E at half engine life for these new P/N Clamps for quite some time and have yet to find a failed one.

The proposed AD seems to include all clamp P/N's, but we still have time to leave comments ("The FAA must receive comments on this AD action by November 2, 2012.")

Seems like we should submit comments and ask to have the new style clamp (P/N 557-369) excluded from the detailed 100 hour inspection and life limit portion of the AD.

A more resonable inspection interval could be the visual inspection of the entire exhaust system at 100 hours, and the detailed inspection of the exhaust system at 1000 hours and the life limit of the new style (P/N 557-369) should follow the recommendations of Piper MSB 644E per Table 1: "Routine inspection per Maintenance Manual/Service Manual instructions. Replace on condition. (no life limit)"

At the proposed AD stands, taking the V-Band clamp off every 100 hours seems a bit excessive. The clamps installed on our engines have been torque checked and visually inspected per MSB 644E at half life and last the entire overhaul interval of the engine,

We install new clamp when the engine is changed, so we have self life-limited the clamps to the engine TBO.

Joe M Miller
Warbelow's Air Ventures, Inc
Fairbanks, Alaska

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[jmmiller]

Hello all!

Just submitted the following in response to the proposed AD:

In response to the proposed airworthiness directive Docket No. FAA-2012-0983; Directorate Identifier 2012-CE-004-AD:

This proposed AD seems to include all clamp P/N's. However, AD 82-16-05 R1 and Piper Mandatory Service Bulletin 644E specifically relieve the repetitive detailed inspections of clamp P/N 557-369.

We respectfully request that this proposed airworthiness directive be changed to reflect Piper Mandatory Service Bulletin 644 (as revised) recommendations for each part number clamp, and to extend the visual and detailed inspections as described below:


1. A visual inspection of the entire exhaust system at 100 hours or every other engine inspection event if the owner has the aircraft maintained by an Approved Airworthiness Inspection Program (AAIP).

2. Extend the detailed inspection of the exhaust system to 1,000 hours. At that time, remove the clamp and perform the inspection detailed in paragraph (h) of the proposed AD.

3. Finally, the life limit of the new style (P/N 557-369) should follow the recommendations of Piper MSB 644 (as revised) per Table 1: "Routine inspection per Maintenance Manual/Service Manual instructions. Replace on condition. (no life limit)" or at a minimum, replace at engine change.

As the proposed AD stands, taking the V-Band clamp off every 100 hours seems a bit excessive, and will, most assuredly, subject the clamp to a high degree of stress by removing and reinstalling it so often.

The clamps installed on our engines are torque checked and visually inspected per MSB 644E every detailed engine inspection per our Approved Airworthiness Inspection Program. This interval seems to be frequent enough to insure that the clamps maintain their integrity.

In addition, we require a detailed inspection of clamp P/N 557-369 per Piper MSB 644E at half engine life. Since initiating this regimen, we have not found any clamp failures in our fleet of Piper Navajo Chieftains. Currently we fly over 8,500 hours annually.

In addition to the regular inspections, we install new clamps at engine exchange time, so we have self life-limited the clamps to the engine TBO, thereby assuring that we have no clamps older than the engine on which it is installed.


Sincerely,

Joe M Miller
Chief Inspector
Warbelow’s Air Ventures, Inc
Fairbanks, Alaska

Please feel free to cut, paste or copy, but please comment to this proposed AD. We have until November 2. Submitting on the website is a piece of cake. Took me less than 10 minutes.

goto: www.regulations.gov Follow the instructions for submitting comments. Just enter FAA-2012-0983 when asked. Click on the COMMENT button on the right.

Thanks,

Joe M

Attachments: