Newb's questions....

[eeyore]

 

Greetings:

I was recently bitten by a Mooney bug and am contemplating a purchase of an E or F.  I hope you can help me with a few questions. 

1.       Besides 208B, what other SAs , in your opinion, should be completed before a purchase?

2.       Compressions…..The aircraft I’m currently looking at has a Mattituck engine.  It was installed in 2001. The log indicates that every year compression dropped by about 1. Current compressions are 71-72. The engine has 850 hours.  With some TLC, is it likely to make to the TBO? 

More questions are sure to come…..

 

[gregwatts]

I would be more concerned about that engine than SBs. SB 208A & B are very important......but it's the ADs that matter.

The compressions should be higher than that....I would certainly invest in a good prebuy inspection.

[Ned Gravel]

Eeyore:

I second the very thorough pre-purchase inspection.  It will save you a ton of money now and heartache later on.  Find a reputable mechanic. 

Before I bought mine, I looked at eight Mooney C and E models and inspected (to varying degrees) five of them. All failed the pre buy - but after the pictures were sent to the owner of the last one, he agreed to cover the cost of repair of the airworthiness issues.  Lowered his price accordingly and I upped the contribution for some other nice-to-have items.

My E model has served me well ever since.  There have been issues, but nothing to do with the state of the aircraft at purchase.

[jetdriven]

#1, look beyond the paint, seat leather, and low low hours, and consider hours in the past few years.  Airplanes that sit more than 14 days at a time or log less than 100 hours a year can be big trouble.  Like have to overhaul the engine for 25K because the cam failed trouble.  Or corrosion trouble.

1. Thats the big one.  The biggest thing is complete logs that show everythign done to the plane. An airplane with only one entry per year, the annual, is going to be trouble.

2.  Compressions are a number only.  Were they done hot? Within 5 minutes of running? Were the ring gaps lined up and low?  My doc has a Beech that had 40 PSI on one cylinder. He flew it WOT for 20 minutes it improved to 75.  A compression test can detect a cracked head or a burned valve (0 PSI), otherwise, take it into context. A low number solely  on its own is not reason enough to pull a cylinder.

TLC on an air-cooled aircraft engine means a low RPM start until oil pressure builds, a fair warm up period with aggressive leaning, and a 65-75% power setting continuously and depending on which Allah you worship, more than 75 ROP or LOP and a CHT under 400 f.  Fly it every day, run it hard but not hot, it will last past TBO.

Running it on the ground, pulling the prop through if it sits a few days, running "a gallon an hour more than book values", for example, are a death sentence.  The aircraft must be flown every 14 days at a minimum.  Get the CHT and oil temp into the green band and stay there for 30 minutes or more. 

This is my opinion, however.  FWIW.

Quote: eeyore

 

Greetings:

I was recently bitten by a Mooney bug and am contemplating a purchase of an E or F.  I hope you can help me with a few questions. 

1.       Besides 208B, what other SAs , in your opinion, should be completed before a purchase?

2.       Compressions…..The aircraft I’m currently looking at has a Mattituck engine.  It was installed in 2001. The log indicates that every year compression dropped by about 1. Current compressions are 71-72. The engine has 850 hours.  With some TLC, is it likely to make to the TBO? 

More questions are sure to come…..

 

[OR75]

things to look at (beyond the ADs and what was already metionned above):

when were the tanks re-sealed ?

does it have the avionics / panel I want ?  will the mods I will want to make be quantum leap (major re-wiring = big $$$) ? or just incremental (small $). 

Mooneys are awesome machines.

[OR75]

PS: reason I mentionned avionics (and autopilots) my gut feel tell me that most Mooney flyers travel longer distances than others brand C or P.  I have no data on that but just a gut feel from monitoring and talking to ATC Centers  

[eeyore]

Quote: gregwatts

The compressions should be higher than that....I would certainly invest in a good prebuy inspection.

[jetdriven]

Anything over 60 is good according to Lycoming.   If it hasnt flown much, the numbers are not really useful.  Continental did a test where they filed the ring gaps where the engine had 40 PSI compression.  That engine made rated power on a test stand.

[jetdriven]

Ours is a 11 year old, 1400 hour engine and it has mid 70s. 

[jetdriven]

Jim, your engine is not airworthy! It is past the 12 year mandatory bulletin set by Lycoming!

[smccray]

Another datapoint- My engine is ~7 yrs old with 850 hrs.  Mine are all 78-79.

[smccray]

Quote: JimR

I know.  And my airframe has over 10,000 hours on it.  And scary damage history . . . from a mid-air, no less!  And no IFR-certified GPS installed.  Someone will absolutely steal it from my estate one day.         

[jetdriven]

See? I read that airplanes with over 12 years on an engine or damage history are worthless.  Scott, Jim, your airplanes are worthless! Along with mine! 

 

But Scott and I just bought ours, so if they were worthless, and someone just bought them.  Well.  Umm.

[smccray]

Quote: jetdriven

See? I read that airplanes with over 12 years on an engine or damage history are worthless.  Scott, Jim, your airplanes are worthless! Along with mine! 

 

But Scott and I just bought ours, so if they were worthless, and someone just bought them.  Well.  Umm.

[sleepingsquirrel]

Quote: jetdriven

See? I read that airplanes with over 12 years on an engine or damage history are worthless.  Scott, Jim, your airplanes are worthless! Along with mine! 

 

But Scott and I just bought ours, so if they were worthless, and someone just bought them.  Well.  Umm.

[Mooneymite]

Compression numbers by themselves really don't mean much.

If there are low compressions, the important thing to determine is where the air is going.  Is it going by the rings, or is it going out through the valves?

A simple determination in most cases.

Unless there is a valve problem, most engines' compression comes up as the engine is flown more regularly.  Sometimes a piece of carbon or lead under the exaust valve will make a cylinder read low...there's a simple procedure to clean it off.

And as another poster has mentioned, when and how the compression check is done can vary the numbers significantly.

Compressions are just one indicator in engine condition.  Don't ignore them, but understand what they're telling you.

 

[N601RX]

There is a lot of information in older threads on buying mooneys that you will want to read.

Look beyond the compressions on cylinder health.  They are just one piece of the puzzle.  Our plane had good compressions for a high time engine(lower 70's) but was using 1.5 quarts of oil hr.  When we removed the cylinders we found several broken rings. Other than the high oil usage the engine ran fine and appeared to make full power.

[eeyore]

Thanks for all your input. I'm trying to convince the seller to let me do a 100 hr inspection at Certified Center.

[danb35]

If the seller won't allow a pre-buy at a facility of your choosing (within reasonable distance), don't walk away--run.

[rbridges]

Quote: eeyore

Thanks for all your input. I'm trying to convince the seller to let me do a 100 hr inspection at Certified Center.

[aviatoreb]

Quote: jetdriven

[jetdriven]

You got me. 55% power is probably OK too.  The only thing you have to worry about is be sure to run LOP or at peak.  Maybe a  little ROP (GASP!) to keep CHT up.   Also, in cold weather, try to maintain a 250f CHT.  Our 201 will not maintain a reasonable CHT or oil temp at super low power settings.   Now I dont think this matters in the short term, but a few hundred or more hours of "SOP" flying at super low power settings can be bad.

[Gunderbear]

Quote: jetdriven

 

[GeorgePerry]

eeyore

You might want to read this thread.  I think you'll find it useful and informative.

http://www.mooneyspace.com/index.cfm?mainaction=posts&forumid=2&threadid=9

[jetdriven]

Good catch Phil.  I was being sarcastic.  Ours has 12 years, and we are going to run it until it says its time to overhaul. IE metal in filter, cam failure, compressions, oil consumption etc.