Ask Paul: What’s the TBO on my engine?

Q: I have obtained a 1978 Bellanca 7GCBC with a Lycoming 0-320-A2B engine manufactured in 1977. I am attempting to learn more about this engine, including why the log book contains an entry at the 1,200 hour mark showing the engine as being “on condition” but I have been unable to determine why.

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Ask Paul: Fly more, get longer TBO?

Q: I bought my first plane, a 1981 Cessna T182RG, in May 2012. I have been flying this plane frequently and have put over 300 hours on it in the last calendar year. I can tell you that in 2005 it received a factory remanufactured engine from Lycoming and at the 1,000 hour mark got a complete top end overhaul. Now Lycoming shows the TBO at 2,000 hours, but I have found documentation from Lycoming that put the TBO at 2,200 hours providing you are running at 40 hours a month. For me that translates to the more you run the engine the more hours you can squeeze out of it.

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Ask Paul: What’s causing intermittent roughness?

Q: I am an European-based A&P with a customer who is experiencing intermittent roughness and loss of rpm (200) typically close to the top of climb on a long climb out. The roughness goes away once it is throttled back, and it does not occur all the time. The snag can’t be produced on the ground. The aircraft is just off annual check and had the 1,000 hours mag inspection carried out, apart from various other visual inspections, plus the routine other items.

I’ve thought about the possibility of a sticky valve, an issue in the carb venturi or some issue with the mags, but thought if it were any of these that the issue would be there all the time?

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Does flight school’s 172 need new rings?

This question was initially sent to our fuels and oil expert Ben Visser, who passed it on to our engines expert Paul McBride for further comment.

Q: Our flight school has a Cessna 172N with an O-320 H2AD. The engine was rebuilt 120 hours ago after cam/lifter failure. The engine uses one half quart of Aeroshell 100 Plus every hour! Oil analysis iron ppm is very low. Compression was 75-78 at 100 hour. Do you think that the rings did not seat? Do I pull the cylinders for new rings and hone?

Denney Marsh, Hemet-Ryan Flight School 

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Ask Paul: Upgrading to a wide deck engine

Q: I read your article from the Oct .7, 2009, issue of General Aviation News on Wide Deck vs. Narrow Deck Lycomings with great interest. I am trying to figure out one detail that I think your article answers, but I just want to make sure.

I have a 1960 PA-22 Tripacer that originally came with a 150-hp O-320-A2B ND engine. It is ready for a major overhaul, and my IA recommends that I upgrade to a WD O-320-B2B engine.

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What are the best options for overhaul?

Q: My question seeks your advice about an overhaul on our Lycoming O-320-H2AD. As background, we have a 1980 C172N that’s been owned since new. It’s always been hangared, never been a flying club or training airplane, is not used for commercial purposes, and has 2,420 TTAFE tach time.

The engine is the original H2AD and it has not been topped. [Read more…]

Ask Paul: How do I know if this AD applies to my engine?

Q: I’ve heard there is an AD that prevents various Lycoming engines from being signed off as airworthy if the TBO is exceeded. I’ve also heard it doesn’t apply to engines manufactured prior to 1970. If the engine was original in the 1960s but remanufactured after 1970 would this AD still apply or would all parts used for remanufacture be exactly the same as the original parts?


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Ask Paul: What is causing sticking valve?

Q: In 2004, I bought a Lycoming O-320 D1A, via Van’s, and started flying it in January 2005 in a RV-9A. I broke it in according to the instructions (75% or more until oil consumption stabilized). In spite of having an oil filter I always do oil changes at about 30 hour intervals. All through the life of the engine it has used 100LL and the average power (after break in) can be estimated from the fuel consumptions of 5.9 to 6.1 max gph. Cylinder head temperatures during takeoff remain below 400°F on a calibrated (boiling water) steam gauge and at about 350°F in cruise.

In April 2010, at 676 hours, I had a sticking valve. Curiously this manifested itself not at cold start-up but during takeoff.

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