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SFOmm
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Post maitenance test flight

Mon Mar 18, 2019 10:32 pm

About a month ago my Hawaiian Airlines flight from SFO to HNL (an A-330) was canceled because there was a malfunction with the captains joystick. It was discovered as they powered up the aircraft at the gate. After we sat on board for 1.5 hours they announced the joystick was not fixable and a new one would have to be flown in from ATL. We all had to be re-booked on other flights. (I took a United 737-900 to KOA which was my ultimate destination anyway. So other than waiting 6 hours for thew other flight it worked out OK for me).

My question is this: After replacing something as important as the captains joystick would they have to do a test flight without passengers? Seems like a pretty critical piece of equipment. Or as they power up if the computer says it good to go is that it, no test flight needed?
 
Lukas757
Posts: 45
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Re: Post maitenance test flight

Mon Mar 18, 2019 10:51 pm

It should be quite easy to check if the replacement sidestick is correctly wired on the ground, I can’t see the need for a test flight. There is however an example from almost 20 years ago, where maintenance in connection with a side stick almost caused a crash:

https://www.flightglobal.com/news/artic ... 20-130318/
 
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zeke
Posts: 14990
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Re: Post maitenance test flight

Mon Mar 18, 2019 11:50 pm

SFOmm wrote:

My question is this: After replacing something as important as the captains joystick would they have to do a test flight without passengers? Seems like a pretty critical piece of equipment. Or as they power up if the computer says it good to go is that it, no test flight needed?


No.

The system is checked for electrical connection and function then the flight controls are powered up to ensure they move in the correct sense.

Then the pilots will do a further flight control check which is standard before every flight.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
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fr8mech
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Re: Post maitenance test flight

Tue Mar 19, 2019 12:33 am

The maintenance task that necessitate a test flight a limited in nature. I don’t have access to our book at the moment, but the only thing I remember that’s common across all our fleet types is replacing more than 50% of the engines.

Of course, we’ll test fly to validate the repair of chronic problems that only manifest themselves in the air. Those are few and far in between.

Then, there are CAT validation flights, or Flight Confidence Checks of the autoland system. While there are no actual tasks, in our maintenance program, that require an FCC, we may have to do one as part of the corrective action after solving a chronic problem, or after a major maintenance visit. These are typically not test flights; they are CAT III landings performed in a CAT I environment.
When seconds count, the police are minutes away.
It’s hard to win an argument with a smart person, but it’s damn near impossible to win an argument with a stupid person. ~B. Murray
Ego Bibere Capulus, Ut Aliis Sit Vivere
 
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Starlionblue
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Re: Post maitenance test flight

Tue Mar 19, 2019 1:34 am

I'll add that after heavy maintenance, the flight back to base is normally the "test flight".

Sometimes a piece of equipment needs to be checked out, e.g. APU start in flight, and this will be scheduled for the next line flight.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
747Whale
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Re: Post maitenance test flight

Tue Mar 19, 2019 4:03 am

There are certain dedicated maintenance test flights, but but most maintenance does not require a flight. Maintenance signoffs for the most part do not return aircraft to service; they approve aircraft for return to service, and pilots actually return the aircraft to service on the next flight. Open maintenance by that time has been settled and closed.

If a test flight were required to find out if installation of hardware were successful, it would mean that the test flight would be conducted with questionable equipment, which would mean that the maintenance dept had no business releasing the aircraft in the first place. Think about it.

If I'm going to conduct a flight, I need to know before I fly that the aircraft is airworthy....I'm not going to fly it to find out.
 
JHwk
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Re: Post maitenance test flight

Tue Mar 19, 2019 4:48 am

Interesting... some friends were in the exact same situation last week...
 
TTailedTiger
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Re: Post maitenance test flight

Tue Mar 19, 2019 5:40 am

I heard Carrie Underwood is recording a new song for the event of a dual failure. "Jesus Take the Joystick". :duck:
 
stratclub
Posts: 1372
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Re: Post maitenance test flight

Tue Mar 19, 2019 8:25 pm

747Whale wrote:
There are certain dedicated maintenance test flights, but but most maintenance does not require a flight. Maintenance signoffs for the most part do not return aircraft to service; they approve aircraft for return to service, and pilots actually return the aircraft to service on the next flight. Open maintenance by that time has been settled and closed.

If a test flight were required to find out if installation of hardware were successful, it would mean that the test flight would be conducted with questionable equipment, which would mean that the maintenance dept had no business releasing the aircraft in the first place. Think about it.

If I'm going to conduct a flight, I need to know before I fly that the aircraft is airworthy....I'm not going to fly it to find out.


Also, if we do not know the function of a switch, we do not flip it to find out. :biggrin:
 
fdxtulmech
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Re: Post maitenance test flight

Tue Mar 19, 2019 10:29 pm

Most of the time it is the operators GMM (General Maintenance Manual) that will specify conditions where a test flight is required beyond anything called out in the AMM (Aircraft Maintenance Manual). The AMM usually has very few, if any requirements for a flight. Some will have certain calibration flights if a major structural repair has been done to wings, stabilizers, something that could change the flight characteristics by being out of symmetry. Most operators have some sort of OCF (Operational Check Flight) program after letter checks, heavy maintenance, mods, etc... and a FCF (Functional Check Flight) program for specific situations like replacement of more than half the engines, all three gear removed, calibration after horizontal bearing fitting replacement, etc... Most of the time it is really up to the operator.
 
strfyr51
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Re: Post maitenance test flight

Tue Mar 19, 2019 10:40 pm

SFOmm wrote:
About a month ago my Hawaiian Airlines flight from SFO to HNL (an A-330) was canceled because there was a malfunction with the captains joystick. It was discovered as they powered up the aircraft at the gate. After we sat on board for 1.5 hours they announced the joystick was not fixable and a new one would have to be flown in from ATL. We all had to be re-booked on other flights. (I took a United 737-900 to KOA which was my ultimate destination anyway. So other than waiting 6 hours for thew other flight it worked out OK for me).

My question is this: After replacing something as important as the captains joystick would they have to do a test flight without passengers? Seems like a pretty critical piece of equipment. Or as they power up if the computer says it good to go is that it, no test flight needed?

the replacement of a single joystick does not require a test flight. However? Replacing Both Joy sticks would. Just as replacing a single Engine does not require a test flight but replacing Both engines would.
 
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Starlionblue
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Re: Post maitenance test flight

Tue Mar 19, 2019 11:42 pm

Sidestick. It's a sidestick. ;)
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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zeke
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Re: Post maitenance test flight

Tue Mar 19, 2019 11:51 pm

strfyr51 wrote:
the replacement of a single joystick does not require a test flight. However? Replacing Both Joy sticks would. Just as replacing a single Engine does not require a test flight but replacing Both engines would.


I don’t see why both of those situations would need a test flight where we are. Sidesticks and engines can be tested on the ground. The golden rule is only things which cannot be tested on the ground are tested in the air.

We only do test flights where we will deliberately turn off systems (like a pressurization leak check), or outside the normal envelope (determining minimum speed or over speed ), deploy the RAT, or other specific local airworthiness requirements (like a functional check of GPWS modes every 3 years).

The sidesticks would need a dual inspection flight control check which is a standard procedure. Replacing both engines would require an ETDO verification flight, but not a test flight. Engines are run in a test cell and then on the aircraft on the ground. In both cases after the maintenance is completed the technical log would say the aircraft is released into service in the normal category.

But I cannot speak for what all regulatiors would require, the local airworthiness requirements vary.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
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fr8mech
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Re: Post maitenance test flight

Wed Mar 20, 2019 1:08 am

zeke wrote:
Replacing both engines would require an ETDO verification flight, but not a test flight.


There are 2 specific conditions in our GMM that require a test flight:

-Engine removals involving more than 50% of the aircraft's engines at a single time.
-Post long-term storage.

The "at-the-discretion-of" conditions are:

-When major repairs are made or structural members are replaced and there is reason to believe the flight characteristics of the aircraft could have been changed.
-When vibration or abnormal operating characteristics are displayed that can't be confirmed on the ground AND flight operations determines the aircraft is unsafe for continued service.

And, my favorite:

-Any other condition which may require a test flight, as determined by Aircraft Engineering & Maintenance managers.
When seconds count, the police are minutes away.
It’s hard to win an argument with a smart person, but it’s damn near impossible to win an argument with a stupid person. ~B. Murray
Ego Bibere Capulus, Ut Aliis Sit Vivere
 
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Starlionblue
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Re: Post maitenance test flight

Wed Mar 20, 2019 1:33 am

Ah yes. The good old catch-all just in case clause... :)
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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zeke
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Re: Post maitenance test flight

Wed Mar 20, 2019 2:34 am

fr8mech wrote:

There are 2 specific conditions in our GMM that require a test flight.


Well that’s what it says in your manual says, does not mean it is required by every operator under different regulators. GMM is very FAA specific.

I can understand post repair or post modification as that may involve testing something that cannot be tested on the ground.

Replacing engines and sidesticks are standard maintenance tasks, unlike repairs or modifications.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
EMBQA
Posts: 7858
Joined: Sat Oct 25, 2003 3:52 am

Re: Post maitenance test flight

Wed Mar 20, 2019 7:10 pm

As someone that has signed off for close to 100 Maintenance Test Flights, it all comes down to each individual airlines operating manual. Many items can be tested on the ground, as the Sidestick you mentioned, but some do require a test flight. There are many good examples listed above..some that come to mind for me.. Duel Engine change, both Elevators, both ailerons..after paint because everything was removed.
"It's not the size of the dog in the fight, but the size of the fight in the dog"
 
twincommander
Posts: 230
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Re: Post maitenance test flight

Fri Mar 29, 2019 6:45 pm

Depends on the issue. Some carriers will allow an ETOPS confidence check, which may be nothing more than flying to the 60 min limit line, then continuing unless a fault occurs, then doing a return to field. Others fly the aircraft "locally" for some time to verify proper operation.

Carrier specific rules that are government approved.

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