Bad Engine News Before Its Time

Unexpected Bad Engine News... Before Its Time: Your Choices And Our Suggestions On Handling The News Your Engine Just Might Need To Come Apart Early
(Revised April 3, 2002)

Our First Blush Advice: Don't Necessarily Take The Quickest Way Out... The Local or "on the scene" A&P May Not Be Your Best Choice!

Giving "blanket engine advice" on this topic is difficult and perhaps even dangerous, so we will assume certain things are a given:
1) Your engine isn't simply "worn out/timed" or at 2/3rds or more towards an O/Haul and has been opened in the last 15 years or so.
2) You are getting somewhat accurate and honest advice from a competent source as to it's (apparent) malady
3) The problem doesn't necessarily and absolutely "ground" the aircraft where it sits even though the investigating A/P may wish to to think so...(more on this later). OR
4) If your Mooney is truly "grounded", you would consider seeking the advice and council of a second or third expert even if it means you may end up shipping the engine (and/or select components) away for evaluation.

Get The Best Diagnosis Your Can And Consider Your Immediate Alternatives
melot175.jpg (9377 bytes)

First off, your prime mission at hand is to determine the actual "real world" level of seriousness of the reported or suspected* engine malady. This will probably mean you need to get a second opinion (or more) from somebody possibly somewhat removed from the economic consequences of making the decision directly. Not all A&P's are engine experts, nor can they be especially on your particular M20s' engine. For example, low compression especially on a cylinder or two, doesn't necessarily render the engine un-airworthy on the spot unless there is a good chance to suspect internal mechanical problems which can't "fix themselves" such as a broken ring, chronically stuck valve, or a severely burned valve etc. which can get worse fast.
*Many times common problems turn out to be nothing at all but something a few flights around the pattern may cure.

For example, many reports of low compressions or a marked level of "metal in the oil/screen/filter" are actually "fixed" by cautiously flying a few hours and checking the symptom(s) again. No compression whatsoever however, may mean the problem should be investigated prior to flying, especially any flight more than a simple conservative keep the runway in sight, "around the patch" flight to see if it helps. Putting compressed air into the cylinder and listening at the exhaust system or oil crankcase breather should confirm the source of the leakage. Stiff or "bound" main or rod bearings, valve train or cam mechanical problems, and catastrophic amounts of metal in the oil, mean an instant tear-down (T&I) on the spot of the entire or a part of the engine.

No matter who removes the engine from your Mooney, the market and GA industry has changed in the last 5-10 years or so to the extent that many A&P's no longer feel comfortable (or are equipped) to do an engine T&I, cylinder O/Haul, or let alone a complete major overhauls in-house. In many respects this is good as we now have many niche specialty shops who specialize in engines and are recognizable by most future buyers of your Mooney. . However, who you choose is perhaps just as vital as what you have them do.

What To Expect If You Ask The Engine Factory:

Most times, factories will advise you to disassemble and inspect (T&I) your engine unless the problem is unmistakably minor in nature, and clearly not apt to get worse by continued operation. Keep in mind, they are trying to second guess your A&P over the phone long distance, and they are not there with "hands on" your engine. In addition, some A&Ps are not known for their verbal communication skills and thus can't accurately convey all necessary information to a factory service rep. Thus in reality, many times tech reps will not therefore be privy to important information or nuances of your particular engine which you and/or your shop has. Most of the time the engine manufacturer will advise the landmark conservative approach of recommending to do a T&I, as not to do so will increase their potential liability and they nearly always tend to error on the safe side. Be prepared for this type of advice.

On the other hand, few if any engine shops will suggest you fly a Mooney to them if they sincerely suspect the flight would put you in danger. However, many times the local shop on the scene will lead you to believe that your Mooney simply shouldn't be flown anyplace unless the problem is rectified. You will most likely need expert advice to make the choice. Remember, many times local generic shops only exist through the occasional accident/incident and/or engine problem which happens at their front door via normal traffic at their airport.

If the problem is upper-end related, it is perfectly acceptable to remove any or all cylinders while the engine is still attached to your Mooney. Actually there isn't much duplication of efforts here as along with the baffles etc, with any T&I they would have to come off anyway. If you find yourself in this position, try to get a credit on labor from the engine shop if you have your local A&P do some of the disassembly beforehand. Some will issue a credit, some may not.
Note: Pictured above top to bottom are: Charlie Melot, Terry Capehart, Tom Rouch

Picking A Engine Repair Facility:
Who does the T&I or resultant overhaul work and exactly what kind of overhaul is done, (and how it is documented) could very well affect the value of your Mooney long-term. Only in rare circumstances would I recommend you always have the local (incident scene) FBO or shop do the repairs just because the incident happened at their front door. If at all possible, you should consider transporting your prop strike Mooney to the location of a well known engine shop or a "Mooney specific" shop. Sloppy or "botched" T&Is are not uncommon. In fact, once the engine is opened, the owner is tied down to the shop in question as will be faced with many choices and will be in need of good sound council. So, pick your T&I or overhaul facility carefully.

In short, many times a sharp engine shop can actually return an engine in better condition after the incident than before. Many times spending money to up-grade the T&I to full major overhaul at least a "power section" overhaul, is money well spent. In fact, if there ever was an opportunity to spend "smart money" on your Mooney this may be it!

A Little Known Engine T&I/O/Haul Choice Which Cans Save You Thousands:
Full OEM Service Manual Spec. "0" Time O/Haul FWF
vs
A "Power Section Only" O/Haul

Torn between a full FWF (Firewall Forward) O/Haul and a T&I (the latter of which adds nothing to the value or utility of your Mooney), a "middle of the road" option we often suggest may be to only overhaul the "power core" of the engine only, and so mark the logs.

We define a "power section overhaul" as an overhaul the "power section" or basic engine itself such as crankcase and internal case components as well as the "upper end" or cylinders etc., and skip the "bolt-on" accessories (such as: prop governor, alt, starter, fuel system, hoses, cables, engine Lord mounts, etc.) which can be done later anytime w/out removing or disassembling the engine.

This practice is however approaching a "gray area" with the FAA and OEM's as to if it can actually be termed an "official" overhaul, as the engine manufacturer typically stipulates in their Service Manuals (SM) a minimum component replacement o/haul list and that an overhaul needs to have all accessories overhauled or replaced. Make no mistake, you can't skimp on INTERNAL engine component/parts and still have any hope of calling it an "Overhaul" later on.

Frankly, we feel most A&P's as well as future owners would recognize a "power section" overhaul for what it is, and that is definitely "counts" in the SMOH consideration, adds value, and can be up-graded later on to a complete FWF overhaul. Think of it as a progressive overhaul.... Even most conservative shops would confirm that if you perform all the necessary steps called-out in the OEM SM concerning the engine proper, and only omit the "bolt-on" external accessories, once you do the remaining accessories etc. later on you would have then (retroactively) complied with the intent of the OEM's and the work completed should be termed a complete FWF O/Haul at that time. It is important a "power section overhaul" not be confused or misrepresented later on with a true FWF (firewall forward) overhaul which does meet OEM specs for the term "overhaul".

Alternatively, if you only do a T&I and even though you replace the bearings etc., but omit even one mandatory replacement component or procedure as called out in the OEM SM, technically you have not done anything other than a T&I and thus your engine's time has not been extended. Many times a few hundred (or a thousand or so) spent at the time of the T&I can allow the work being done to qualify as a "power section O/Hall" and thus increase the value of your Mooney dramatically and allow you to recapture much of money spent.
We advise you acquaint yourself with your alternatives BEFORE your engine is reassembled.

Again, the advice offered here is general in nature and we will be upgrading this section and adding PDF reprints of related articles in the near future. As always, we welcome opposing opinions and your suggestions, observations, and comments. Keep tuned as more data and articles become available. We also welcome suggestions from engine shops and A&Ps. Please email us with your input.