Infrequent flyer

[wrbix]

First, my apologies if this has been beaten to death in the past, but a search led me nowhere; so here goes:

I see alot of comments here about avoiding AC which have been infrequently flown. Can someone summarize why please?

Gasket/seal deterioration?

Cylinder rust?

Fuel tank deterioration?

Something else?

If an AC has had appropriate annuals and excellent compressions, does this reassure?

Thanks in advance

Bill

[rbridges]

someone will give a better explanation, but here's my 2 cents.

 

People have made comments about electronics/avionics needing to be turned on occasionally.  Not exactly sure why, but I've seen it mentioned a few times.  Also, you need oil thrown up into the engine every now and then to keep things lubricated and coated.  Moisture doesn't get removed when the plane doesn't fly.  Other things like batteries going bad, tires getting dry rotted, etc can happen from a plane just sitting there.

[The-sky-captain]

I think the biggest reason is corrosion inside the engine and Lycomings seem to fare the worst with the camshaft being the culprit. The engines need to be flown once a week or so at temps hot enough to burn off any moisture in the oil. As long as the plane is hangered and the tanks full I don't think there would be any deterioration of the fuel tanks.

[wrbix]

Advantage to the timing of coming up on TBO soon I presume?

[1964-M20E]

Generally all the things you mentioned and you can add lubrication of pivot points, internal corrosion of the airframe from the elements and critters as a counter to this investigate about the use of corrosion x or something similar. If the plane has averaged less than 10 to 15 hours a year you might want to be a little more cautious. However, you should also consider where and how the plane has been stored during that time outside in a very damp area not as good as in a dry hangar. Like anything else a car, motorbike, boat, household appliance if it sits without use for very long times and if it sits outside the elements takes their toll.

[Scott Aviation]

I think some other things to consider with sitting are carbs and fuel injection servos and dividers seals drying out. Boost pump seals. Fuel pumps. Prop seals. These are all things that will nickel and dime you to death in airplanes that have sat for long periods of time with a coating of fuel inside and lack of lubrication and use.

[RJBrown]

The climate where the plane was based can be an important consideration. It is unlikly that any rust would intrude into the engine of an Arizona based plane regardless of usage. Where a costal Florida plane that is operated daily will have airframe corrosion even with constant attention and care. I would buy a Colorado hanger queen before any coastal resident. A plane flown once a month in a dry climate may have less corosion that a weekly flier in a humid climate.

[carusoam]

Rust and related cilinder health... When I bought my m20C that sat for a couple years...

-a-

[bd32322]

The climate where the plane was based can be an important consideration. It is unlikly that any rust would intrude into the engine of an Arizona based plane regardless of usage. Where a costal Florida plane that is operated daily will have airframe corrosion even with constant attention and care. I would buy a Colorado hanger queen before any coastal resident. A plane flown once a month in a dry climate may have less corosion that a weekly flier in a humid climate.

Doesnt work that way ..! The moisture comes from the products of combustion and not much from the atmosphere. The products of combustion are in the oil and need to boil off from frequent flying where the oil temps need to reach a critical temp (i hear 180 F) . I wont profess to know what the problem with florida is .. but i think it has more to do with salty water that forms electrolytic reactions on unprotected metal surfaces. As for the original question, my main beef is that an aircraft with a low time engine will be priced accordingly, but with an infrequently flown engine, you will have cylinder wall corrosion which will cause piston rings to wear early (I was told) and then an early top overhaul

[marks]

Oh so slowly fuel evaporates through vents and leaves traces of sludge. Internal engine parts lose their coatings of oil and allow rust. While the previous poster may be correct that most interior engine moisture comes from combustion, it's also true that air with a high moisture content can get into the engine through the crankcase breather and when at night the engine slowly cools, that the dew point can be reached and moisture can condense in the engine. This is less likely in arid areas of the country. In fact, there is a question on the private pilot exam that explains that moisture can condense in the fuel tanks overnight, so that checking the fuel the night before does not constitute an adequate preflight. Condensation is also possible on interior airframe parts such as frame tubes. Lastly, in general I think it's a good bet that airplanes that don't fly simply don't get as much personal attention as compared to airplanes that fly on a regular basis.

[sleepingsquirrel]

http://www.pilotsofamerica.com/forum/showthread.php?t=55959

 

Pictures and all. Engine only no real discussion of airframe.

[bd32322]

Oh so slowly fuel evaporates through vents and leaves traces of sludge. Internal engine parts lose their coatings of oil and allow rust. While the previous poster may be correct that most interior engine moisture comes from combustion, it's also true that air with a high moisture content can get into the engine through the crankcase breather and when at night the engine slowly cools, that the dew point can be reached and moisture can condense in the engine.

That is correct .. Moisture in the air will cause corrosion unless engine parts are coated with fresh oil .. Which comes from frequent flying also

[wrbix]

Thanks for all the input and the link. Overall I'm impressed by abscence of horror stories from infrequent flying.

[carusoam]

You didn't look very hard....

Stuck valve and destroyed cam and how to avoid them are my favorite discussions.

Lycoming engines have had a few issues here over the years. Enough to generate the endless discussion on oil additives.

Or did I misunderstand your statement?

Best regards,

-a-

[The-sky-captain]

My engine was only 600 SMOH when I bought it although it was 12 years old and had only flown 30 hours in the previous year. The first year of ownership was fine but after those 200 hours lots of metal began showing up in the filter and chunks of it in the suction screen. Bad cam= OH. In the end I'm happy I did it because I know how the engine has been treated since OH. 400 hours and going strong. Jetdriven went through a similar ordeal. Buyer beware of infrequently flown planes w low engine times...

[wrbix]

<blockquote class='ipsBlockquote'data-author="carusoam" data-cid="88641" data-time="1359587945"><p>

You didn't look very hard....<br />

<br />

Or did I misunderstand your statement?<br />

<br />

<br />

<br />

Best regards,<br />

<br />

-a-</p></blockquote>

[wrbix]

No, that is why I asked the original question. Searches under a number of search terms never really addressed the issue of low time, infrequent useage. Your input is appreciated and links to the appropriate earlier discussions you allude to would be also. I've not been following this board for long.

[wrbix]

.....and, as you can see, simple things like quoting previous posts are unfamiliar.

[carusoam]

The two topics I can think best describe the issue are cam oxidation and engine overhaul. There are not many, but enough, that indicate that the risk to a Lyc O360 setting for years is quite large.

My O360 stuck a valve when I first purchased it. I knew it sat for a year or two and knowingly (sort of) took on the risk. The situation occurred after several hour long flights.

What i didn't know, is that there is a way to visually inspect the cam and cylinders for oxidation or damage. This is also covered here at mooneyspace.

The good news? We have one member here that has some responsibility for an oil additive to help avoid the corrosion. Find him and ask questions.

Best regards,

-a-

[jetdriven]

Doesnt work that way ..! The moisture comes from the products of combustion and not much from the atmosphere. The products of combustion are in the oil and need to boil off from frequent flying where the oil temps need to reach a critical temp (i hear 180 F) . I wont profess to know what the problem with florida is .. but i think it has more to do with salty water that forms electrolytic reactions on unprotected metal surfaces. As for the original question, my main beef is that an aircraft with a low time engine will be priced accordingly, but with an infrequently flown engine, you will have cylinder wall corrosion which will cause piston rings to wear early (I was told) and then an early top overhaul

 

Worse and more expensive is the cam going bad from disuse. you can change out cylinders as needed for around 1500-2K a piece.  The cam goes bad it starts at ten grand, and 3:1 it is going to be a full major OH at 25K on up.

 

We bought an infrequently flown plane (35 hours the prior year, 75 the year before that), and 250 hours later, cha-ching. 35 grand for a new engine.

 

Now I will say we bought a factory engine and redid everything else, which was all worn out. However, you can skate by on a 23K FWF job, but you may be 400 hours in and have to do it all again because nobody knows the cause of cam and lifter spalling on Lycomings.  I was so disgusted at the matter we solved that failure mode permanently with the roller cam.

 

Our plane was fed a steady diet of Camguard as well, BTW.

[KSMooniac]

Non-engine related concerns are the actuators, pumps, gyros, etc. that need regular "exercise" to move the grease and wet the seals.  Avionics need knobs twisted and buttons pushed, switches, thrown, etc. to keep the corrosion out of the contacts.  None of these items are necessarily show-stoppers, but if buying an idle plane you should be prepared to deal with a lot of nuisance items as you start using it again.  The cost and downtime in the first year of ownership may or may not be worth the reduced price you (should) pay up front.  

[wrbix]

Now that's (last few posts) the kind of useful input I was looking for.

Thanks

[Bob_Belville]

I bought a  '66 "E" a year ago.

 

2700 TTSN, 600 hours on FREM. Always hangered. Clean annuals, IFR certifications and ELT regularly done, and good compressions.

 

The 5 years prior to my purchase it was flown 40, 29, 21, 5, & 43 hours between annuals. I've added 60 hours this year with down time for panel upgrade, empennage shim AD, new exhaust install.

 

Engine has been so far, so good - knock on wood - we'll see if it does a jetdriver swoon. (I did treat it to a set of fine wire plugs shortly after purchase and eliminated a tendency to need to burn off plugs to get a good mag check.) 

 

Other failures which might have been aggravated by prior disuse: Alternator, exhaust system, step retract servo, KNS80, Stormscope. (A Narco HSI was making noise but was running most of the time when I decided to pull whole panel.) Total for all these small items was about 9-10 AMU.