Poor Engine- Yet Airworthy

[Jaybird180]

Hypothetical question:

A plane with a weak running engine goes in for annual. The plane is personally owned and operated strictly for pleasure.

Is this plane considered airworthy?

 

[PilotAlan]

How do you define "weak running engine"?

 

[SCCutler]

I used to fly a 172, engine had 2800 hours or so, folks at the FBO said it was "tired," but it still pretty much made book numbers. These engines sorta work or they don't.

 

[dmccormack]

I used to fly a 172, engine had 2800 hours or so, folks at the FBO said it was "tired," but it still pretty much made book numbers. These engines sorta work or they don't.

Exactly.

Mine has 300 hours and is 70 years old -- but makes all book numbers and idles clean and even, does a 20 RPM drop on each mag, and goes faster when I push forward and slows down when I push back.

We replaced intake tubes during the annual, and a new ignition harness will go one next month, but otherwise it's airworthy or it's not.

 

[steingar]

It's airworthy if the mechanic says it is.

 

[tonycondon]

I used to fly a 172, engine had 2800 hours or so, folks at the FBO said it was "tired," but it still pretty much made book numbers. These engines sorta work or they don't.

my FBO in college had a 172 with over 3000 hrs on it since major. it was the best performing engine in our fleet of 4 or 5 Skyhawks.

 

[ScottM]

What is a weak engine?

 

[rpadula]

What is a weak engine?

One that can't bench press it's own weight?

 

[Dan Thomas]

What is a weak engine?

One that won't achieve the maximum static RPM as defined by the TCDS for the airplane. For a 172M, for instance, you should get not less than 2275 and not over 2375 RPM. Poor compression, weak spark, bad carburetion will all contribute. For a constant-speed setup you might have to dig a little deeper, but manifold pressure figures in as well.

Dan

 

[poadeleted20]

If you have a fixed pitch prop, the only objective criterion is whether the engine makes the prop turn at the minimum specified static RPM during a full-throttle static run-up. If it does, it's probably airworthy (other issues like compression notwithstanding). If not, the aircraft is not operating in accordance with its published limitations, and that means it isn't airworthy.

And make sure you have an accurate tach for this check -- mechanical tachs tend to read lower as they age, and those a couple of decades old or more can read 100-150 or more lower than actual RPM. This could lead you to believe falsely that the engine isn't meeting the minimum static run-up value.

 

[Jaybird180]

So out of spec for published limitations makes it not airworthy...

I think that's the answer I was looking for. Thanks Ron. You're a constant source of knowledge.

 

[Tom-D]

So out of spec for published limitations makes it not airworthy...

I think that's the answer I was looking for. Thanks Ron. You're a constant source of knowledge.

That's pretty much it, The A&P-IA during the annual inspection must declare the aircraft airworthy or not, the requirement comes from the
FAR,43.15
(2) Each person approving a reciprocating-engine-powered aircraft for return to service after an annual or 100-hour inspection shall, before that approval, run the aircraft engine or engines to determine satisfactory performance in accordance with the manufacturer's recommendations of—

(i) Power output (static and idle r.p.m.);

(ii) Magnetos;

(iii) Fuel and oil pressure; and

(iv) Cylinder and oil temperature.


But between inspections it is the Pilot who determines the airworthiness of the aircraft. It is their responsibility to insure the aircraft is safe to fly.

If it won't meet the numbers given in the Type certificate or placards posted in the POH or displayed in the aircraft it is not airworthy and probably not safe to fly.

As a pilot it is your responsibility, 91.3

 

[PaulMillner]

>> Poor compression

Compression typically doesn't affect power output. It does give you early warning that a cylinder may be fix in' to break.

 

[PaulMillner]

>> Poor compression

Compression typically doesn't affect power output. It does give you early warning that a cylinder may be fixin' to break.

 

[bbchien]

How do you define "weak running engine"?

......One that has denied for engine health insurance.

 

[Tom-D]

And make sure you have an accurate tach for this check -- mechanical tachs tend to read lower as they age, and those a couple of decades old or more can read 100-150 or more lower than actual RPM. This could lead you to believe falsely that the engine isn't meeting the minimum static run-up value.

let us assume that your IA has proven the tach to be indicating wrong, Is that aircraft airworthy?

91.205

 

[NC Pilot]

......One that has denied for engine health insurance.

Which is why we need socialized aircraft maintenance in this country. Think how much safer it will be to fly.

 

[COFlyBoy]

let us assume that your IA has proven the tach to be indicating wrong, Is that aircraft airworthy?

91.205

I've wondered that too. I don't have an answer though. Is inaccurate the same as inoperable?

I know a guy who's airspeed indicator was reading 10 mph high. The issue was noted in the report for the pitot/static check. The IA signed off with a caveat that the aircraft could not be used for IFR.

The guy has since had the ASI repaired and has been relearning the approach numbers. I think the ASI may have been reading wrong for more than 10 years.

 

[COFlyBoy]

Which is why we need socialized aircraft maintenance in this country. Think how much safer it will be to fly.

That would be awesome. Then every American would help pay for aircraft maintenance. We need more talk about the rising cost of plane care.

 

[Henning]

Hypothetical question:

A plane with a weak running engine goes in for annual. The plane is personally owned and operated strictly for pleasure.

Is this plane considered airworthy?

The IA should perform a run up check in which one of the criteria is that it makes static RPM. If it does not meet the specifications set forth in the manufacturers instructions then no, it is not airworthy.

 

[poadeleted20]

Is inaccurate the same as inoperable?

In a case regarding a mixture cable, the NTSB decided that if "it was not working properly, or as designed," it was "inoperable."
http://www.ntsb.gov/alj/alj/O_n_O/docs/aviation/4965.PDF
And that's the only definition of "inoperable" I can find in the case law. So, what's the book tolerance on accuracy for that particular tach?

 

[Tom-D]

In a case regarding a mixture cable, the NTSB decided that if "it was not working properly, or as designed," it was "inoperable."
http://www.ntsb.gov/alj/alj/O_n_O/docs/aviation/4965.PDF
And that's the only definition of "inoperable" I can find in the case law. So, what's the book tolerance on accuracy for that particular tach?

I wouldn't think the simple mixture cable with 1 moving part that works or not, is the same as a tach that is inaccurate.

What in service calibration do we have on any instrumentation, other than the Altimeter for IFR Ops.

 

[poadeleted20]

I wouldn't think the simple mixture cable with 1 moving part that works or not, is the same as a tach that is inaccurate.

Read the case and see if you still think that's relevant. In any event, it's the only definition I can find in the case law, so it's likely to be the one cited if it goes to that point.

What in service calibration do we have on any instrumentation...

I'll bet there's some in the shop manuals for the instruments themselves. Your local instrument repair station may have them, as may the instrument manufacturer. This may seem excessive work for you, but if you want the answer for a question like this, be prepared to do your homework.

 

[Tom-D]

Read the case and see if you still think that's relevant. In any event, it's the only definition I can find in the case law, so it's likely to be the one cited if it goes to that point.

I read the case, the mixture was sticking, that was inop as seen by the NTSB, but is it required under 91.205 for flight? could it have been placared out IAW 91.213

I'll bet there's some in the shop manuals for the instruments themselves.

That's not the point, if any instrument is removed for service it must meet the bench/overhaul requirements for return to service, but while it is in service, what are the owners requirements to have it calibrated?

Your local instrument repair station may have them, as may the instrument manufacturer. This may seem excessive work for you, but if you want the answer for a question like this, be prepared to do your homework.

No repair station requirements are required to be complied with in the field by any A&P or A&P-IA. It's just a matter is it working as it should, or not? Is it safe to fly or not?

If you are the A&P-IA doing the run up after the annual and are determining if the aircraft is airworthy, and you can't see the RPM required, because the tach is wrong is that aircraft airworthy?

 

[poadeleted20]

If a sticking mixture control makes it "inoperable" and thus makes the airplane unairworthy in the eyes of the FAA, then I cannot possibly see how placarding it "inop" could somehow make the plane legal again. Beyond that, your statements are disingenuous. If there are tolerances specified for return to service in the shop manuals, you can bet those are what the FAA will use to decide if the tach is "working properly, or as designed" if they get involved.

Also, if you check 91.205(b)(2), you'll see that an operable tach is required for each engine.

 

[Tom-D]

If a sticking mixture control makes it "inoperable" and thus makes the airplane unairworthy in the eyes of the FAA, then I cannot possibly see how placarding it "inop" could somehow make the plane legal again.

If the Case you brought up had the A&P done the proper paper work and gotten a ferry permit the FAA would not have had a case. but he didn't and got busted.

Beyond that, your statements are disingenuous. If there are tolerances specified for return to service in the shop manuals,

This is the same old Prop argument, the A&P can't work on props or instruments in the field, they either work or not.


you can bet those are what the FAA will use to decide if the tach is "working properly, or as designed" if they get involved.

Also, if you check 91.205(b)(2), you'll see that an operable tach is required for each engine.

BTDT check my original question. ( post #15)

What is the owner / operators requirement to have any other instrument except the altimeter calibrated ?

 

[poadeleted20]

What's the purpose of a special flight ("ferry") permit? To allow flight of an airplane which isn't legally airworthy, although is in condition for safe flight under limited circumstances. QED.

As for your second question, see 91.7(b).

 

[COFlyBoy]

91.7 (b) pretty much gives the responsibility and discretion to the pilot. So, between annuals I am the one who verifies continued airworthiness.

It still doesn't really provide any insight on the required accuracy of an instrument. I am sure most of the manufacturers have numbers used for repair and overhaul. But, I've not seen many instructions on how to determine in-service accuracy.

On a side note. I was doing my IR stage 2 check with another CFII and he asked me about the IFR instrument check that we do on the ground (and I usually forget to do during the taxi) and whether or not those checks are airworthiness issues. He said according to FAR we can continue flying if the AI tilts, or the DG precesses, or the VSI doesn't read zero. All of those checks are for the pilot to determine airworthiness, but they are not required by regulation. Might required some 'splainin' if you bent metal though.

 

[Tom-D]

What's the purpose of a special flight ("ferry") permit? To allow flight of an airplane which isn't legally airworthy, although is in condition for safe flight under limited circumstances. QED.

you are exactly right, had the owner/Pilot/A&P gotten a ferry permit, they would have no problems with the FAA.

But your case also indicates the practice to fly with discrepancies was the major cause for the Judge to up hold the decision.

As for your second question, see 91.7(b).

91.7
(b) The pilot in command of a civil aircraft is responsible for determining whether that aircraft is in condition for safe flight. The pilot in command shall discontinue the flight when unairworthy mechanical, electrical, or structural conditions occur.

That gives the Pilot discretion to fly any unairworthy aircraft, provided the proper ferry permit and a signature of any A&P that determines that aircraft with the discrepancies, is safe to fly for the 1 flight necessary to get it where it can be repaired.

To answer the question you seem to avoid, there is no requirement for the owner or operator to have the Tach calibrated, they also have no method to know it's reading wrong, other than seeing that the reading is obviously wrong.

 

[poadeleted20]

On a side note. I was doing my IR stage 2 check with another CFII and he asked me about the IFR instrument check that we do on the ground (and I usually forget to do during the taxi) and whether or not those checks are airworthiness issues. He said according to FAR we can continue flying if the AI tilts, or the DG precesses, or the VSI doesn't read zero. All of those checks are for the pilot to determine airworthiness, but they are not required by regulation.

If you're suggesting that one can skip those checks because no regulation specifically requires them, I think the FAA might pick that bone with you. Those are mandatory tasks on the IR practical test, and probably listed in the checklist in your POH "Normal Procedures" section. If nothing else, I think the FAA could make a case for "careless/reckless" if you didn't do them before launching IFR.

As for what constitutes acceptable tolerances for those checks (i.e., whether those instruments are "airworthy"), the FAA provides guidance on them in a number of publications like the AIM, IFH, and IPH, and probably some AC's. While those pubs are not "regulatory," by definition, they do provide acceptable means of complying with the regs (e.g., the max 5 degrees of tilt on the AI during turns on the ground). If you choose to use other, looser criteria (e.g., 10 degrees of AI tilt), and the FAA somehow became involved, you'd be on your own to show how your personal, less strict criteria still met the regulatory standards for safety, especially since...

Might required some 'splainin' if you bent metal though.

 

[poadeleted20]

91.7
(b) The pilot in command of a civil aircraft is responsible for determining whether that aircraft is in condition for safe flight. The pilot in command shall discontinue the flight when unairworthy mechanical, electrical, or structural conditions occur.

That gives the Pilot discretion to fly any unairworthy aircraft, provided the proper ferry permit and a signature of any A&P that determines that aircraft with the discrepancies, is safe to fly for the 1 flight necessary to get it where it can be repaired.

That's what I said. And it reinforeces my statement that the PIC is responsible if the plane is flown with the tach "inoperable" other than on a ferry permit.

To answer the question you seem to avoid, there is no requirement for the owner or operator to have the Tach calibrated, they also have no method to know it's reading wrong, other than seeing that the reading is obviously wrong.

That's not the point. If you don't know it's not working right, you don't know it's not working right. The question under discussion is what happens when you do find out it's not reading properly, because at that point, you know that it's "not working properly, or as designed," which makes it "inoperable" per the FAA/NTSB definition. Since the tach is required for all flight by 91.205, that makes the plane "unairworthy," and other than as authorized for 1-time flight on a ferry permit as needed to reach a repair facility, it is a violation of 91.7(b) to fly it.

As for what level of error makes it "inoperable," I don't know, and would have to do more research to find out, and the answer might be type-specific, too.

 

[COFlyBoy]

As for what level of error makes it "inoperable," I don't know, and would have to do more research to find out, and the answer might be type-specific, too.

Hmm. For the VSI we just check it to see what the new zero is (ie. you're just recalibrating / applying an offset). Same could be done for a tach. Ours reads a little less than 2650 when the prop is turning 2700. Its been checked and signed off by the AI so I consider it airworthy because he signed it.

I'm going to check my shop manual to see if there is any info.

 

[COFlyBoy]

OK, I checked the shop manual for the PA-32-260.
The tachometer trouble shooting table has 5 trouble conditions:
1- No reading
2- Pointer oscillates excessively
3- Indicator changes in climb
4- Pointer jumps at idle
5- Tachometer cable breaks

No indication of required accuracy and no info on what "excessively" means.

 

[poadeleted20]

Hmm. For the VSI we just check it to see what the new zero is (ie. you're just recalibrating / applying an offset). Same could be done for a tach. Ours reads a little less than 2650 when the prop is turning 2700. Its been checked and signed off by the AI so I consider it airworthy because he signed it.

Tach is required for even Day VFR. VSI isn't required even for Night IFR (at least under 91.205 -- your AFM may say otherwise).

 

[poadeleted20]

OK, I checked the shop manual for the PA-32-260.
The tachometer trouble shooting table has 5 trouble conditions:
1- No reading
2- Pointer oscillates excessively
3- Indicator changes in climb
4- Pointer jumps at idle
5- Tachometer cable breaks

No indication of required accuracy and no info on what "excessively" means.

When you check the shop manual on the tach itself, let us know what it says.

 

[RotorAndWing]

When you check the shop manual on the tach itself, let us know what it says.

"picking fly sh*t out of pepper again?"

 

[Tom-D]

"picking fly sh*t out of pepper again?"

What ratio of sh-- to Pepper make is worth while to pick sh--

 

[RotorAndWing]

What ratio of sh-- to Pepper make is worth while to pick sh--

I'm sure there's a manual to specify that.

 

[Tom-D]

That's not the point. If you don't know it's not working right, you don't know it's not working right.

As for what level of error makes it "inoperable," I don't know, and would have to do more research to find out, and the answer might be type-specific, too.

What criteria would you use to say it's not working right? If it is Pilot discretion how can the FAA say different?

Don't tell me shop manual because I know you ain't got one, nor does any pilot that doesn't own a Instrument repair facility.

who says your tach is right, just because it reads what you think it should?

 

[poadeleted20]

What criteria would you use to say it's not working right? If it is Pilot discretion how can the FAA say different?

91.7(b) does not say it's "pilot's discretion" to decide whether something is airworthy or not. It says it's the pilot's responsiblity to ensure that it's airworthy. Very big difference.