Thoughts please? ...Pilots... AME's...?

[Mitch Cronin]

Change both engines on a twin... Do you think a test flight should be required?... Have you heard of that practice?

[AME]

Mitch

I know there is a list of maintenance items that require a test flight for the Dash 8 and a double engine change was one of these items, I can't remember for sure but I believe it can be found in the Maintenance program (CMP).

You should also be able to find in you Maintenance control manual a flight test requirement section.

I for one would not release a twin engine aircraft after a double engine change without a test flight.

hope this helps.

[Vsplat]

Mitch, I'm not an AME but I vote a strong yes to a test flight. There may be additional requirements if it's an ETOPs aircraft.

I don't know what generation of aircraft you're discussing, but some aircraft have FMS's that 'learn' from the engines for fuel consumption, performance, etc. This can result in reduced capability immediately following an engine change, until the database is re-populated from run time datapoints.

Cheers

-Vs

[Request deviations]

Mitch,

In the corporate (604) world, our MCM requires a test flight after a single engine change let alone a dual change.

Glyn

[conehead]

We recently recieved a directive from Airworthiness that we require a "ETOPS Verification" accomplished by flight crew after a single engine change on a ETOPS aircraft. Not sure about your question. Sounds like a good idea, but hey, that's common sense talking. Call M.O.C. or your Airworthiness guy for info.

[Canus Chinookus]

1 engine change might be debatable, but a double?! Seems crazy to me, but hey, I try to apply common sense when I can.

[DEFCON]

Who is, or where does it say that a test flight isn't necessary?.

[boestar]

Change both engines on a twin... Do you think a test flight should be required?... Have you heard of that practice?

Absolutely it is required. I believe that is a CARs requirement is it not?

[conehead]

Mitch, why did you ask this question? Are you guys doing a double e/c?

[boestar]

Just as a note .... I HATE THE CARs... It is virtually impossible to do a search without comming up with hundreds of totally irrelavent documents. I cannot find a reference but I know there is something.

What aircraft are you pulling both motors on?

[Guest rattler]

Mitch: is this what you were looking for? Note Condition (4).

Maintenance Release

571.10 (1) No person shall sign a maintenance release required pursuant to Section 605.85 or permit anyone whom the person supervises to sign a maintenance release, unless the standards of airworthiness applicable to the maintenance performed and stated in Chapter 571 of the Airworthiness Manual have been complied with and the maintenance release meets the applicable requirements specified in section 571.10 of the Airworthiness Manual.

(2) Except as provided in subsection (4), a maintenance release shall include the following, or a similarly worded, statement:

"The described maintenance has been performed in accordance with the applicable airworthiness requirements."

(3) No maintenance release is required in respect of any task designated as elementary work in the Aircraft Equipment and Maintenance Standards that is performed by

(a) in the case of a glider, a balloon or an unpressurized small aircraft that is powered by a piston engine and not operated pursuant to Part IV or VII, the pilot of the aircraft;

( in the case of an aircraft operated under Part IV or VII, a person who has been trained and authorized in accordance with the flight training unit’s or the air operator’s maintenance control manual (MCM), approved under Subpart 6 of Part IV or of Part VII, respectively; or

(amended 2000/12/01; previous version)

© in the case of an aircraft operated pursuant to Subpart 4 of Part VI, a person who has been trained in accordance with those sections of a private operator's operations manual that contain details of the operator's maintenance control system.

(4) Where a person signs a maintenance release in respect of maintenance performed on an aircraft, the satisfactory completion of which cannot be verified by inspection or testing of the aircraft on the ground, the maintenance release shall be made conditional on the satisfactory completion of a test flight carried out pursuant to subsections 605.85(2) and (3), by the inclusion of the phrase "subject to satisfactory test flight".

(5) No person shall sign a maintenance release in respect of specialized maintenance unless the requirements of section 571.04 have been met.

[boestar]

Rattler:

That is ok for conditional release but the engines can be fully tested on the ground.

Once upon a time there was a reference to the twin engine dual engine change requirement ffor a test flight. I suspect that this is now covered in the appropriate MPM or MCM.

Generally the reason is to give comfort to the crew that the installations were safe and an engineer was a required participant.

I personally would NOT release the aircraft without the Subject to Satisfactory Test Flight statement.

B

[Guest rattler]

I guess it is all in how you read or apply:

the satisfactory completion of which cannot be verified by inspection or testing of the aircraft on the ground

Just trying to help Mitch find the correct CAR. I am not qualified to answer the question posed.

I would wonder however if the test cell record would be considered proof that the engines were operating properly along with the subsequent run-up after installation on the aircraft. Perhaps the correct answer is in the company Maintence Manual?

[Guest]

Hi Mitch,

excellent question. I have not yet had to deal with this situation, but I would go to the airworthiness controller and ask him/her. I suggest Derek G as he is quite knowledgeable.If need be, contact Transport Canada and ask the question.

I wish I had the answer, but will try to do some research.

[Mitch Cronin]

Ok, thanks all for your responses. I'm not sure how much I can say without getting in trouble, but maybe if we all just don't mention any airline names it might be alright eh?

The "airworthiness" folks where I work say "Heck no, why would you want to do that?"

Their argument (which includes knowledge of CAR's and, of course, our own maintenance control manual) is that we can test everything on each engine completely, on the ground, so what would we want to do a test flight for?

My response was in a few parts:

1- Not "everything" can be tested on the ground... some things change in varying ambient pressures, and even due to changes in inlet pressures due to forward velocity... (maybe a stretch, but still true)

2- Even if we can't come up with a good reason to believe we haven't tested "everything" on the ground, changing both flippin' power plants provides all sorts of avenues for human factors to have allowed errors to creep in.

3- Even if we're damned sure we've covered all bases, it's been "common practice" since Christ was a cowboy to do a damned test flight after two engine changes on a twin (except, apparently, where I work), and that practice was almost certainly written with people's blood. So just because I can't come up with a reason that convinces you, it doesn't mean there isn't good reason to do so.

Anyway, in the end I told them if I was to be the fella releasing the airplane, I was damned well going to write it in the book: "Maintenance check flight required due dual engine change". ...and they were going to do so, but things dragged on (parts issues mostly) and it's likely the test flight that had been scheduled to happen this evening (I have no idea if that was because I told them I'd insist, or not) will probably not happen, and someone else will wind up kissing the bird off later tonight. So, unless things drag on some more, it's a moot point for now. (Though I'm fairly confident it will come up again)

I'm really glad to see I'm not the only one. These guys almost had me thinking I was crazy.

..oh ya... the bird is one of those big twins the B company builds. (still being a little cryptic to try to stay out of trouble... once bitten, twice shy sort of thing you know)

Cheers,

Mitch

[mrlupin]

Usually, those engines have been test run at a powerplant overhaul center. The test cells are quite suited for max power operation so it is very unlikely anything will go wrong once they have been ops checked.

That being said.... certain companies have a tendency of robbing parts left right and center from spare engines..... companies that do this should probably test fly the engine, even after a good session of ground testing....

I too would like a test flight after such a double engine change.

Did you know that the A320 series aircraft doesn't require a test flight after a heavy check? The aircraft gets torn apart, both engines come off, all flight controls, landing gear etc.... and no test flight required. The AMM is worded in way to allow that discretion....

Éric

[Mitch Cronin]

I should also say Thanks Rattler... I had found that already, but I'll bet it took me 10 times as long as it took you to find... Damn I hate plowing through tc.gc.ca for anyhting at all. I'm not good at it, and they sure don't seem to make it easy.

I was really hoping to find something that made it an absolute must.

I remember very well a grizzled old geezer of an instructor, who'd cut his teeth on big, round, piston thumpers and big, beautiful V12s, ...standing at the front of a classroom saying - or growling, "if you change both engines on a twin you go for a test flight" ...and he meant YOU go for a test flight. "If you screwed up bad enough to kill anyone you should be with them."

I think he was right on both counts.

[Mitch Cronin]

Aargh, sorry Eric... I posted too slow....

These engines are "untested" prior to our own testing (being partially rebuilt at our own facility). We do the power assurance runs and all other testing.

[DEFCON]

"Did you know that the A320 series aircraft doesn't require a test flight after a heavy check? The aircraft gets torn apart, both engines come off, all flight controls, landing gear etc.... and no test flight required. The AMM is worded in way to allow that discretion...."

The same people that build the 5 minute standby battery powered emergency gyro's?

[DEFCON]

"Did you know that the A320 series aircraft doesn't require a test flight after a heavy check? The aircraft gets torn apart, both engines come off, all flight controls, landing gear etc.... and no test flight required. The AMM is worded in way to allow that discretion...."

Seriously though; the same people that brought you the "pilot proof plane" also consider it, the "mtx proof plane"? WOW!

[conehead]

Mitch; I would suggest you speak with some folk in Airworthiness a little higher up the food chain. Personally, I feel a test flight is in order. I'm sure some folk in Flight Ops would feel the same way.

[Mitch Cronin]

I was told the whole food chain had been involved. ...and that's really why I posed the question here, I was hoping to get some feedback from pilots as well.

Cheers,

a good night's sleep awaits.... I'll never forget what it's like not to be able to.

[RFL]

Mitch;

Thank you for your dedication to safety. While it may not be a technical requirement I believe it is 100% prudent to complete a test flight. We may remember an L-1011 very nearly downed by a simultaneous faulty oil filter change on all 3 engines. Good night!

[Maverick]

Hey Mitch, I've been looking through our manuals tonight. I can't find it but I know that we do do a test flight for a double engine change. This has never been questioned by anyone in any department at WJ.

[boestar]

the biggest reason behind the test flight after the dual engine change is that HUMANS may have made the same error on BOTH engines during installation. Since humans make mistakes it stands to reason if one mistake is made on the left it could be repeated on the right.

I agree with sending the releasing engineer on the flight as well. this helps solidify the safety aspect. I will do like Im the one flying it...cuz I am.

Once upon a time an engineer flew on all post heavy check test flights. I don't think that happens anymore.

We should always err on the side of safety. The plane should be flown prior to revenue operation...Period. I think all AMEs would back you up on that.

B