We are suffering an engine problem that surfaced after annual inspection that has our shop stumped. EGTs and TIT have increased over 100 degrees Fahrenheit in all phases of flight, with cruise true airspeed down 10 knots.

Here are the specifics:

• Aircraft: Mooney Bravo M20M
• Engine: Lycoming TIO-540AF1B
• EGTs and TIT up over 100 degree Fahrenheit in all phases flight

o Take-off TIT: 1,400, previously 1,300
o Cruise TIT 8,000 to 11,000: 1,670, previously 1,550
• Cruise true airspeed 8,000 to 11,000 MSL down 10 knots
• CHTs: no change
• Fuel flow: no change, 15.3 GPH in cruise
• Manifold pressure: no change
• RPM: no change
• GAMI spread increased from 0.5 to 0.8 GPH

Reported engine maintenance performed during the annual inspection:

• Compressions: tested, normal
• Injectors: cleaned, replaced seals
• Two spark plugs replaced
• Induction air filter replaced
• Prop pitch cable replaced
• Waste gate lubricated after becoming stuck during first post-annual test flight

Savvy profiles were flown pre- and post-annual. I have five years of consistent JPI data.

This problem was submitted to Savvy and GAMI. Their recommendations were followed without success. Recommendations included:

• Check ignition timing
• Check upper deck pressure
• Check magneto pressurization
• Pressurize induction system, check for leaks

Any suggestions will be greatly appreciated.

Ask if the shop used a bead blaster to clean the plugs. This can create all kinds of issues. One operator would bring his turbo lycoming in to the shop running fine LOP. Out of the shop it wouldn't run LOP. The shop was cleaning the plugs with a champion blaster.

I hope that's your problem.

Try a new set of Tempest plugs and report back.

Timing may be retarded. Shops keep setting 25 degree lycomings to 20 degrees timing, which causes all those things. Check the star washers on the mags as well, they can't be reused and people keep having mags fall out of th accessory case.

I owned a Brave for years great plane.

I think they messed up and put the injectors back in the wrong cylinders.

That's the reason for the increased spread.

At the risk of declaring victory before the test flight, I believe our problem is solved.

Timing was the obvious problem, but our mechanic insisted we were properly set at 20 degrees -- checking it multiple times. Unfortunately, he was using a timing line that was misaligned after he had installed an overhauled prop almost a year ago.

Like so many things in aviation, it took a chain of events spanning almost a year to create this problem. Our failure to challenge the accuracy of a timing line made solving the problem far more time consuming than necessary.

Lesson learned for me. I hope sharing helps others.

Thanks everyone for joining our troubleshooting effort!

Blue skies,
David

At least it wasn't a MIF! Instead it was a MIP. Maintenance induced Problem.

Glad you finally got it sorted out.

1550 TIT and 15.3 GPH ?
Is that LOP ?
RPM ?

I saw that too. My Bravo required 19.4 GPH in cruise. As you know, few Bravos run well LOP.