Failures after Annual Inspection

[MikeOH]

No, pursuing this with the shop is NOT going to be a solution (i.e. no admission they had anything to do with it; geographic inconvenience/hassle factor).  So, I'm on my own and any help would be appreciated!

Two issues:

First issue that NEVER existed before: Loss of sidetone when transmitting and a low level background hiss (yes I've played with all the squelch and volume settings.)

Second is the FS450 and Insight G3 fuel flow readings now bounce all over!  I mean like from 2.5 gph to 18 gph!!  Continuously for a 2 hour flight.  To be fair this happened ONCE to me a couple of months back for a short time (<5 minutes) on a 1 hour flight, and not as dramatic swings.  Haven't seen it before or since; until now.

Other pertinent information:

The shop was in the engine compartment removing and reinstalling the exhaust system.

The shop was under the panel fixing an intermittent power boost warning light switch.

During post maintenance run-up the CB for the audio panel (and ??) tripped.  They delayed finishing the annual while "troubleshooting" but failed to find anything.  The CB did NOT subsequently trip so they didn't pursue it further.  When I asked if they had any idea what caused it, I got a response of "Nope". It is important to note that in 6 years of ownership I've only had a CB trip ONCE after maintenance where another shop tore my panel apart looking for a static system leak which turned out to be the unseated alternate air valve! (That 'work' caused a short in the gear warning system) 

 

I am hoping someone has seen these or similar issues and can point me to where to look.  Thanks!

[carusoam]

Mike,

What audio panel / intercom / headset do you have?

For some reason, getting side tone to work right is a chore….

Best regards,

-a-

[cbarry]

It sure sounds like a lack of grounding issue—possibly for both.

[MikeOH]

1 hour ago, carusoam said:

Mike,

What audio panel / intercom / headset do you have?

For some reason, getting side tone to work right is a chore….

Best regards,

-a-

@carusoam

It's an old PS Engineering PM1000II.  I use a stone-age passive headset; not one of them thar new-fangled noise-cancelling dealies

Reminder: Everything worked perfectly on the flight to the shop for annual, and did NOT on the return flight.  Nor have I previously had that issue.

[MikeOH]

1 hour ago, cbarry said:

It sure sounds like a lack of grounding issue—possibly for both.

@cbarry

I suspect you may be correct; while they were messing around under the panel they messed up a ground; likely on the verge of failing.  That would explain the one-time issue I had with the fuel flow.  Now, how to find it!!!??!!!

OTOH, how does a bad/open ground reconcile with their report of tripping the audio panel CB?  That seems more like a temporary short.

[carusoam]

58 minutes ago, MikeOH said:

@carusoam

It's an old PS Engineering PM1000II.  I use a stone-age passive headset; not one of them thar new-fangled noise-cancelling dealies

Reminder: Everything worked perfectly on the flight to the shop for annual, and did NOT on the return flight.  Nor have I previously had that issue.

@Mscheuer we might have a guy that knows something about PSEngineering equipment around here…

its always good to have his input… it helps sell his awesome equipment.

Best regards,

-a-

[kortopates]

You most likely have a loose connection, or crimp at fuel flow transducer. This is actually pretty common.


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[Ragsf15e]

I’ve had a similar audio issue after maintenance and it was due to the ignition leads not being tightened.  In fact the top 4 were all loose.  Might just want to check there’s no fraying and all are secure at the mag and plugs.

[ilovecornfields]

I had a similar problem after annual with the fuel flow and it was just a loose cannon plug. I’m sure you already did it, but probably worth taking the cowling off and seeing if there’s any obvious loose connections.

That’s certainly frustrating when your plane leaves the shop with issues it didn’t arrive with.