Post Maintenance Test Flight

[Dickard]

What's the best practice for post maintenance test flights.  Oil changes, just fly in the pattern or do a Savvy Aviation type profile?  I just had an exhaust gasket blow out on #4.  Dropped the exhaust pipes on 2 and 4, smoothed the flange mating surfaces, and replaced with new gaskets.  I ran the engine up on the ground with my A&P watching from outside.  I feel like this test flight is a little different than a post oil change flight.  Should I stay in the pattern?  Do a short climb/cruise flight?  Both?  Thoughts?

[Yetti]

I do one or two fast taxi.   Then bring it back and look it over.    Then take it up to 7000 over the airport.   I had a mechanical fuel pump show it was failing after bringing it out of annual and doing the flight above the airport.

[Rick Junkin]

My conservative post-mx procedure is to climb to about 3000' AGL over the field and orbit within easy gliding distance. At 3K AGL that's 5 miles or less. That gets me out of the traffic pattern both in altitude and lateral displacement and gives me enough room to exercise everything and use any power setting I need to stress the repaired systems and components.

I see you're at KCOS - give Springs tower a call and tell them you need to do a post-maintenance flight and ask them what works best for them to keep you out of their normal traffic flow. The conversation is also a good way to let them know you aren't just up for a few laps around the pattern and give them the sense that if things go poorly you'll be looking for their help to get back on the ground quickly. The odds against something going wrong increase astronomically when everyone is prepared to deal with it. At least that's been my experience.

Cheers,
Junkman

[Dickard]

14 minutes ago, Rick Junkin said:

My conservative post-mx procedure is to climb to about 3000' AGL over the field and orbit within easy gliding distance. At 3K AGL that's 5 miles or less. That gets me out of the traffic pattern both in altitude and lateral displacement and gives me enough room to exercise everything and use any power setting I need to stress the repaired systems and components.

I see you're at KCOS - give Springs tower a call and tell them you need to do a post-maintenance flight and ask them what works best for them to keep you out of their normal traffic flow. The conversation is also a good way to let them know you aren't just up for a few laps around the pattern and give them the sense that if things go poorly you'll be looking for their help to get back on the ground quickly. The odds against something going wrong increase astronomically when everyone is prepared to deal with it. At least that's been my experience.

Cheers,
Junkman

There's also Springs East just on the edge of the Charlie airspace in case something goes wrong.  I like your advice though about talking to the tower crew.

[bradp]

Something like an oil change (no suction screen removal)- run engine.  Check for leaks.  There’s only two places you’ve messed with.  Quick drain and oil filter adapter.  No leaks.  You’ve added oil. There’s not much point in taxiing or flying. 
 

Post engine RR - it’s much more extensive.  First run. Decowl. Inspect. Cowl.  First test / break in flight.  Decowl.  Inspect. Prior to my first flight.  Decowl. Inspect.  Post my first flight decowl.  Inspect. 
 

 

[carusoam]

Since your new exhaust connections are going to be the focus of the test….

Make sure you have your CO detector running for any early warning signs it can give…

Pp thoughts only…

-a-

[Guest]

On 8/20/2022 at 2:31 PM, Dickard said:

What's the best practice for post maintenance test flights.  Oil changes, just fly in the pattern or do a Savvy Aviation type profile?  I just had an exhaust gasket blow out on #4.  Dropped the exhaust pipes on 2 and 4, smoothed the flange mating surfaces, and replaced with new gaskets.  I ran the engine up on the ground with my A&P watching from outside.  I feel like this test flight is a little different than a post oil change flight.  Should I stay in the pattern?  Do a short climb/cruise flight?  Both?  Thoughts?

Why the need for a test flight in this case?  If your maintainer verified that the cylinder flanges are flat, the exhaust stack flanges are flat, he installed new gaskets new lock washers and nuts, torqued them the the Lycoming manual,  carried out a run up and rechecked his work before installing the cowl and signed to logs, what more would a test flight reveal?

[PT20J]

I don’t see much need for a post maintenance test flight unless I’ve had something major done like replacing an engine (or cylinder). A thorough ground run up to operating temperature and a leak check seems enough after an oil change. I flew for two Part 135 operations and the only time they required a test flight after maintenance was after an engine or cylinder replacement or if the controls has been disconnected or adjusted. Otherwise it went right back onto the line flying passengers.

Skip

[bradp]

Oh paint.  Definitely paint.  Test fly with maybe a high speed taxi prior to pattern.   I had an absolute wild ride after my painter randomly reinstalled my ailerons and provided me with a similarly random aileron rigging.  Plane wanted to turn >45 left and I limped it back around.  

[Dickard]

Perhaps I'm reading FAR Part 91.407 too strictly.  Re-reading it, that most certainly sounds like the case.  However, I'd rather be overly cautious.  My next planned business flight is over the Sangre De Cristo range of 14ners and then dropping down into Los Alamos.  Not a flight where you want to discover there's a problem.

[jaylw314]

On 8/20/2022 at 12:30 PM, Yetti said:

I do one or two fast taxi.   Then bring it back and look it over.    Then take it up to 7000 over the airport.   I had a mechanical fuel pump show it was failing after bringing it out of annual and doing the flight above the airport.

The number of "fast taxi" accidents I hear about at EAA meetings is disturbing enough to avoid that as a routine.  Granted a number of them may simply be kit builders who subconsciously pull up during a fast taxi because they can't resist  Still, I'd say there's not much advantage to a static runup and definitely safer while you're distracted by other stuff.

After every annual, I fly at least a couple circuits in the pattern to convince myself things are ok.  If you're at a towered airport, warn them--I forgot once and asked them for a landing gear check, and they asked if everything was okay.

[carusoam]

Fast taxiing has so many unfamiliarity challenges with it…

Like braking distance as we near the far end of the runway….   
 

We need a nose gear brake for that….

and a prop that goes into beta…

Best regards,

-a-

[ArtVandelay]

Oh paint.  Definitely paint.  Test fly with maybe a high speed taxi prior to pattern.   I had an absolute wild ride after my painter randomly reinstalled my ailerons and provided me with a similarly random aileron rigging.  Plane wanted to turn >45 left and I limped it back around.  

How come your preflight inspection didn’t find this?

Everyone does thorough preflights after maintenance, yes?

[bradp]

4 hours ago, ArtVandelay said:

How come your preflight inspection didn’t find this?

Everyone does thorough preflights after maintenance, yes?

Because it was only a tiny bit of deflection off to produce a larger effect. Not apparent on a visual inspection. You really needed the rigging boards to tell something was off.  Also how the ailerons sit is different when air loaded is something else I learned from this.   

[Rjfanjet]

I think the reg says test flight before carrying passengers after a major modification. We put a STOL kit on a 182. This is the caliber of work that requires the flight at the absolute minimum. The rest is up to you. The flight should also be logged in the maintenance log book.

[Hank]

I always make a test flight after oil.chamge and after annual. So far, that's the only major work I've had to do, beside OH a magneto away from home.