Tony_Scarpelli
Pattern Altitude
- Joined
- Feb 4, 2010
- Messages
- 1,645
- Location
- Wichita, Kansas
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Display name:
Tony_Scarpelli
Hello guys,
9 years ago I bought a Cherokee with run out engine. 7000 TTAF, 20xx TBO. Fresh annual on my home field, compressions were 68, 69, 74, 76.
I wanted to learn to fly so I figured I would get my PPL and then worry about OH engine rather than chance screwing up a good engine....what did I know?
I flew every day for 1 1/2 months got my license. Inspected compressions again and they all went up: 74, 72, 76, 77. So I continued to fly the plane with occasional checks.
The two owners before me used Marvel Mystry oil 4 oz per 10 gallons in the fuel. So I continued the practice. Fast forward to the beginning of this year I had 3400 hrs on it, and it passed annual with flying colors. Over the 9 years I had rebuilt all the accessories figuring those are the things that get you broke down on an away field.
4 years ago I bought Turbo Comanche so I finally let go of my first air plane. It was very hard for me as I became more attached to it then some of my siblings. I sold it to a flight school and they rented it out for 300 hrs in a few months. Finally their IA was afraid to sign it off.
I told him to find another IA (or 2nd A&P to sign off the discrepancy engine) as I felt he was too conservative.
Compression were all still in the mid 70's and within 5 psi from the top to the bottom so a nice grouping. Boroscope showed normal usage. Valve guides/wabble test ok, Oil analysis, which I had performed every 100 hrs as long as I owned the airplane (with normal oil changes), showed gradual but normal wear meaning no reason to suspect any problems. NO metal in the filter nor screen. Never a hickup in running, no oil leaks, no over heated cyclinders. So why rebuild it?
Airlines did lots of studies on infant mortality or mechanic induced failures as well as TBO of parts/engines and found that a running engine with no signs of problems is more likely to continue running and not fail than a newly rebuilt engine will within the first 200 hrs.
I recommended flying it another year. Yesterday I went into the shop to say high and N6496R's 8500TTOE, 3400TBO hr O-320 was disassembled on the table, cleaned and measured parts. All parts were not only within serviceable limits but most are within new limits. No pitting, no corrosion, no spalding.
I am glad I don't have to buy the $8000 worth of parts to put it back together again. I couldn't help myself, busting the chops of the IA I have known for 9 years. His only response was "well, now we know."
My opinion is this: First Cherokee 150 hp engines are near bullet proof engines no doubt about it. Second high time flying regularly is a much better guarantee of condition than anything else. Third Marvel Mystery oil either works really well or at very least does no harm. Fourth, he may be a mechanic, A&P or IA but you as the owner know your engine. You should never substitute your knowledge for his when you know your plane. This is qualified with the following: I am no mechanic, I hate doing Oil changes on my own cars and have only done one on my Cherokee in 9 years. I did however take the time to read everything I could on Lycoming 0320 engines, talk to every mechanic I met in 9 years about same, take the Savvy Aviators maintenance cost reduction seminar on "Condition Based Maintenance." And am active in the decision making and supervision of excellent maintenance of my planes.
I know for a fact that many mechanics advice just like many lawyers advice seems more geared towards their financial means and needs than conditions at hand. I'm not bad mouthing Mechanics nor Lawyers it is just a human response to filter our advice through our own needs.
Prepare yourself to protect yourself.
9 years ago I bought a Cherokee with run out engine. 7000 TTAF, 20xx TBO. Fresh annual on my home field, compressions were 68, 69, 74, 76.
I wanted to learn to fly so I figured I would get my PPL and then worry about OH engine rather than chance screwing up a good engine....what did I know?
I flew every day for 1 1/2 months got my license. Inspected compressions again and they all went up: 74, 72, 76, 77. So I continued to fly the plane with occasional checks.
The two owners before me used Marvel Mystry oil 4 oz per 10 gallons in the fuel. So I continued the practice. Fast forward to the beginning of this year I had 3400 hrs on it, and it passed annual with flying colors. Over the 9 years I had rebuilt all the accessories figuring those are the things that get you broke down on an away field.
4 years ago I bought Turbo Comanche so I finally let go of my first air plane. It was very hard for me as I became more attached to it then some of my siblings. I sold it to a flight school and they rented it out for 300 hrs in a few months. Finally their IA was afraid to sign it off.
I told him to find another IA (or 2nd A&P to sign off the discrepancy engine) as I felt he was too conservative.
Compression were all still in the mid 70's and within 5 psi from the top to the bottom so a nice grouping. Boroscope showed normal usage. Valve guides/wabble test ok, Oil analysis, which I had performed every 100 hrs as long as I owned the airplane (with normal oil changes), showed gradual but normal wear meaning no reason to suspect any problems. NO metal in the filter nor screen. Never a hickup in running, no oil leaks, no over heated cyclinders. So why rebuild it?
Airlines did lots of studies on infant mortality or mechanic induced failures as well as TBO of parts/engines and found that a running engine with no signs of problems is more likely to continue running and not fail than a newly rebuilt engine will within the first 200 hrs.
I recommended flying it another year. Yesterday I went into the shop to say high and N6496R's 8500TTOE, 3400TBO hr O-320 was disassembled on the table, cleaned and measured parts. All parts were not only within serviceable limits but most are within new limits. No pitting, no corrosion, no spalding.
I am glad I don't have to buy the $8000 worth of parts to put it back together again. I couldn't help myself, busting the chops of the IA I have known for 9 years. His only response was "well, now we know."
My opinion is this: First Cherokee 150 hp engines are near bullet proof engines no doubt about it. Second high time flying regularly is a much better guarantee of condition than anything else. Third Marvel Mystery oil either works really well or at very least does no harm. Fourth, he may be a mechanic, A&P or IA but you as the owner know your engine. You should never substitute your knowledge for his when you know your plane. This is qualified with the following: I am no mechanic, I hate doing Oil changes on my own cars and have only done one on my Cherokee in 9 years. I did however take the time to read everything I could on Lycoming 0320 engines, talk to every mechanic I met in 9 years about same, take the Savvy Aviators maintenance cost reduction seminar on "Condition Based Maintenance." And am active in the decision making and supervision of excellent maintenance of my planes.
I know for a fact that many mechanics advice just like many lawyers advice seems more geared towards their financial means and needs than conditions at hand. I'm not bad mouthing Mechanics nor Lawyers it is just a human response to filter our advice through our own needs.
Prepare yourself to protect yourself.
