70/80 is the new 60/80

[Let'sgoflying!]

I bought a new Eastern Technologies E2M diff press tester with master orifice as recommended by TCM, and followed the instructions on performing the master orifice test which came with it.

The M.O. test instructions do not say how to evaluate the test or what to do with the result.
I got 76/66 or so and when the LH gauge is brought up to 80 as specified I get 70 on the right hand gauge.
Presumably the M.O. simulates a leaky cylinder.
I called Eastern and they said that the way I use the "70psi" is that is the new cutoff for a bad cylinder. (Yes I know all the arguments about a cylinder might be just fine at 50 but let's skip that for this discussion and assume we want a specific number below which we no longer have faith in the cylinder's future.)
I said, what about the 60/80 that many, including the manufacturers used to use as the cutoff? He said that was for the old 0.040" tester that people commonly used. The SB above notes the MO test as defining the new lower limit.

Any comments?

(my guess is a lot of mechanics still use the 040" orifice on their compression tests in large bore engines)

 

[denverpilot]

I believe TCM has had a document out about how to test the engines for a long time that originally called for the master orifices. Don't they?

(Not a mechanic but I do remember that there were a lot of engines "not passing" compression checks long ago, and TCM put out a test procedure.)

 

[Tom-D]

http://www.tcmlink.com/pdf2/SB03-3.pdf

 

[denverpilot]

Thanks Tom.

 

[Let'sgoflying!]

I believe TCM has had a document out about how to test the engines for a long time that originally called for the master orifices.

Yes, that is the link I posted in the first post, you can click the colored text and it will pop up.

 

[Henning]

I bought a new Eastern Technologies E2M diff press tester with master orifice as recommended by TCM, and followed the instructions on performing the master orifice test which came with it.

The M.O. test instructions do not say how to evaluate the test or what to do with the result.
I got 76/66 or so and when the LH gauge is brought up to 80 as specified I get 70 on the right hand gauge.
Presumably the M.O. simulates a leaky cylinder.
I called Eastern and they said that the way I use the "70psi" is that is the new cutoff for a bad cylinder. (Yes I know all the arguments about a cylinder might be just fine at 50 but let's skip that for this discussion and assume we want a specific number below which we no longer have faith in the cylinder's future.)
I said, what about the 60/80 that many, including the manufacturers used to use as the cutoff? He said that was for the old 0.040" tester that people commonly used. The SB above notes the MO test as defining the new lower limit.

Any comments?

(my guess is a lot of mechanics still use the 040" orifice on their compression tests in large bore engines)

Interesting that your cylinder guys give opposite advise to Continental. They don't really care what it's holding, they only care about where it's coming from. Valves leaking=no good; rings they found through testing that even cylinders tested at 40/80 made the same power as 75/80. If it's leaking from the valves, missing, or using too much oil, I believe those are the new "60/80".

BTW, Did your cylinder guy have a child recently?

 

[timwinters]

It's my understanding that the TCM doc has now been made a part of Cessna's mx manuals and thus is the only legal way to perform a compression check at annual and/or 100 hour inspections.

I can't personally swear to the above, but that's what a good friend who is an A&P recently told me.

 

[Tom-D]

It's my understanding that the TCM doc has now been made a part of Cessna's mx manuals and thus is the only legal way to perform a compression check at annaul and/or 100 hour inspections.

I can't personally swear to the above, but that's what a good friend who is an A&P recently told me.

since when are manufacturers manual required to be adhered to during annual/100 inspections?

have your A&P-IA show you the requirement by FAR.

I have seen no new ADs that require it.

 

[Let'sgoflying!]

since when are manufacturers manual required to be adhered to during annual/100 inspections? have your A&P-IA show you the requirement by FAR. I have seen no new ADs that require it.

Well, this is what TCM uses, right in that SB to direct one to that conclusion. I suppose someone with lawyerly instincts or training might parse the words to mean otherwise. As in, well the FAA document is only "Advisory"?

F.A.A. Advisory Circular (AC) 43.13-1. Chapter 8, Section 1, paragraph 8-1 states; “ Consult the
manufacturer’s manuals, service bulletins and instruction books regarding the repair and overhaul, inspection,
installation, and maintenance of aircraft engines, for that particular make, model and type of engine.

 

[Tom-D]

Well, this is what TCM uses, right in that SB to direct one to that conclusion. I suppose someone with lawyerly instincts or training might parse the words to mean otherwise. As in, well the FAA document is only "Advisory"?

We all know the ACs are not regulatory.

This is
FAR 43-7/9/13/16

(a) Each person performing maintenance, alteration, or preventive maintenance on an aircraft, engine, propeller, or appliance shall use the methods, techniques, and practices prescribed in the current manufacturer's maintenance manual or Instructions for Continued Airworthiness prepared by its manufacturer, or other methods, techniques, and practices acceptable to the Administrator, except as noted in §43.16. He shall use the tools, equipment, and test apparatus necessary to assure completion of the work in accordance with accepted industry practices. If special equipment or test apparatus is recommended by the manufacturer involved, he must use that equipment or apparatus or its equivalent acceptable to the Administrator.

until such time as the administrator see fit to require us to use the manufacturers manuals and instructions we can use what is out lined in red above.

BUT...

be careful your Cessna could be maintained under an approved maintenance plan.. Plus your aircraft could be under an approved progressive inspection, which could also dictate the required manuals.

 

[RotorAndWing]

It's my understanding that the TCM doc has now been made a part of Cessna's mx manuals and thus is the only legal way to perform a compression check at annual and/or 100 hour inspections.

I can't personally swear to the above, but that's what a good friend who is an A&P recently told me.

Tim,

Your Cessna maybe maintained with the service manual that was provided at the time of manufacture. If Cessna comes out with a revision later you are not bound to such revision unless it's a part of an AD. Essentially the FAA does this to prevent the manufacturers from circumventing the AD process, only the FAA can write regulatory requirements.

Reference FAA Order 8620.2A dated 11/05/2007

Consistent with 14 CFR, a TCDS is part of a product’s type certificate (TC). A TCDS is a summary of the product’s type design. It is used primarily by authorized persons during initial or recurrent issuance of a Standard Airworthiness Certificate. It is neither a regulation, a maintenance requirements document, or a flight manual document. As such, for aircraft holding a valid and current airworthiness certificate, a TCDS should not be used as a sole source to determine what maintenance is required or what the flight operations requirements are. Any language on a TCDS, by itself, is not regulatory and is simply not enforceable. There must be a corresponding rule to make any language on the TCDS mandatory. For example, there is a mention of “operating limitations” on most TCDS. The corresponding rule for “operating limitations” is 14 CFR § 91.9(a) which states, “Except as provided in paragraph (d) of this section, no person may operate a civil aircraft without complying with the operating limitations specified in the approved Airplane or Rotorcraft Flight Manual, markings, and placards, or as otherwise prescribed by the certificating authority of the country of registry.” Without § 91.9, the TCDS requirement to comply with operating limitations would not be enforceable.

TCDS notes are intended primarily to provide information on the various requirements for issuing an airworthiness certificate as well as the type and location of various technical documents used to operate and maintain the product. Some OEM’s have placed mandatory language such as “shall,” “must,” and “will” on their TCDS that imply that compliance with TCDS notes is mandatory. However, in the absence of regulatory language, or an AD that makes such TCDS notes mandatory, compliance with such notes is not mandatory. It would mean that FAA regulations effectively authorize OEMs to issue “substantive rules,” i.e., it would enable an OEM to impose legal requirements on the public that differ from the 14 CFR requirements. This would be objectionable for two reasons. First, the FAA does not have the authority to delegate its rulemaking authority to an OEM. Second, “substantive rules” can be adopted only in accordance with the notice and comment procedures of the Administrative Procedures Act (APA), which does not apply to an OEM.

http://www.faa.gov/documentLibrary/media/Order/8620_2A.pdf