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Prebuy Examination Services

LSA mechanic So, you've decided to purchase a used Light Sport Aircraft? Excellent choice! New aircraft lose about 10 to 20 percent of their value the moment they are registered for the first time. Since the Light Sport rule is only ten years old, you can now find some fairly new, low-use aircraft at a reasonable price.

If the aircraft purchasing process is new to you, you may be feeling just a bit overwhelmed. Prof. H. Paul Shuch, AvSport's chief flight instructor and director of maintenance, stands ready to assist you in this major decision. Because used aircraft are generally offered for sale "as is," it's important to determine whether your new acquisition is really as advertised. That's where a prebuy examination comes in. Below are a few important points to consider.

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(1) Do Your Own Due Diligence

When you go to buy a plane, it's important to be clear on your exact mission. Keep it in mind when deciding whether a particular make, model, category, and class will meet your personal needs. It's easy to become enamored of a beautiful low-time bird, sitting on the ramp and gleaming in the sun. Gorgeous as it might be, you need to be ruled by logic, not your emotions. Although I will be happy to consult with you, only you can determine if this plane belongs in your hangar. Test fly it (in fact, test fly a whole bunch of aircraft, if you're able). Fly-In events like Airventure, Sun-n-Fun, and Sport Aviation Expo will afford you the opportunity to examine many different aircraft, test fly a few, and narrow down your choices.

Once you select a candidate aircraft, pay close attention to what the seller says about its maintenance history and condition. When you make an offer, it should be conditional upon the aircraft being found as advertised, through an independent examination by the mechanic or shop of your choice. If the seller refuses to let somebody else examine the aircraft, or assures you that such an examination is not necessary, walk away!

(2) Choosing Your Prebuy Provider

The shop or person examining your candidate aircraft works for you, not the seller. As a general rule, the seller and your prebuy specialist should be completely independent from each other. Ideally, the two should never have had any business relationship with each other. From a practical standpoint, this is unrealistic -- the LSA community is small, and everyone in this business knows (and has had dealings with) everyone else. So, determine to your own satisfaction that no conflict of interest exists, that would compromise the independence of the person you're hiring to objectively analyze your intended purchase.

Make sure your prebuy is done by someone familiar with the particular type of aircraft you're considering buying. Special and Experimental Light Sport aircraft especially are manufactured and maintained under rules different from those which apply to certified aircraft. If a given shop has only limited experience with SLSAs, and ELSAs, it may miss something vital which would be instantly evident to one that specializes in this particular category of aircraft.

Make sure the person or shop you select for your prebuy is qualified on the kind of engine used in your candidate aircraft. The Rotax 912 series four cylinder, four stroke opposed engine, for example, powers about 80% of the Special Light Sport aircraft fleet. It is a well designed, efficient and reliable engine, but it is decidedly different from the Lycoming and Continental engines on which most mechanics were trained. Rotax offers four different levels of factory-authorized training, and if you're planning to buy a Rotax powered aircraft, you should seek out a Rotax authorized independent maintenance technician, or a factory designated Rotax independent repair centre.

Once you've selected the appropriate prebuy provider, you will want to get permission from the seller to take your prospective purchase to that mechanic's shop for examination. Examining an aircraft in the seller's facility should be a last resort, as it's difficult for the mechanic to be thorough without access to his or her own tools and equipment -- and nearly impossible to be truly independent when the seller is breathing down the mechanic's neck.

It's a good idea to pick a shop an hour or less (flying time) distant from where the plane is sitting. The seller will probably want to fly there with you, so make sure your selected shop can complete all required tasks within a single business day. In fact, if the seller is unwilling to risk flying the plane with you to your mechanic's facility, you should consider that a red flag -- just walk away!

During the flight to the prebuy facility, take advantage of this opportunity to not only feel how the plane flies, but to test the function of every piece of avionics equipment, and every installed accessory. Consider this an opportunity for an extended, thorough test flight.

If the seller refuses to let the aircraft leave his or her facility for the purposes of a third-party prebuy, or insists that your prebuy agent do the examination in the seller's facility, walk away!

(3) A Prebuy Is Not An Inspection!

In FAA parlance, the word "inspection" has a very specific legal meaning, which has implications for both the mechanic and the owner. When I do an inspection (whether an annual, 100 hour, or some other type of condition inspection), I enter into a contract with the owner, which empowers me (among other things) to ground the airplane if I find it not to be in a condition for safe flight, and to exercise a mechanic's lien against the aircraft if my bill is not paid. Since you don't (yet) own the aircraft in question, you cannot enter into such a contract with me.

(4) An Inspection Is Not A Prebuy!

Sometimes, the seller will offer to deliver the aircraft to you with a fresh annual inspection. Although having the aircraft inspected (and thus blessed for flight for the next year) is beneficial, remember that if it's done by the seller, this does not constitute an independent evaluation by a disinterested party. An inspection and a prebuy look for different things -- the former seeks to determine whether the aircraft is in a safe condition for flight, while the latter seeks to determine if there are any red flags to suggest that maybe you shouldn't be investing in this particular aircraft. If the seller insists that a fresh annual is as good as a prebuy (or better), walk away!

Although they are performed for different reasons, once a maintenance professional has completed a thorough prebuy examination, he or she has already performed about half of the tasks required for a condition inspection. So, if you decide to purchase the subject aircraft, and want a fresh annual, your mechanic can probably finish the job for you. The additional cost (above and beyond what you paid for the prebuy) will generally be about half of what you'd normally pay for an annual inspection. Bear in mind that a prebuy should be converted to an annual only after you close the deal and take possession and title of the aircraft.

(5) A Prebuy Should Be A Search For Dealbreakers

Let's face it; you're considering buying a used aircraft. It may look like new (especially if the seller has done a good job of detailing it), but it's not going to be new. There will inevitably be cosmetic blemishes, and normal wear and tear is to be expected. Tires may be balding, brake pads in need of replacement, oil dirty, and non-structural items may show their age. If you aren't prepared to accept this, you shouldn't be buying a used aircraft.

Things that can easily be remedied with a bit of TLC should not deter you. The purpose of a prebuy is not to nit-pick, but rather to find good reasons why you should not be considering this plane. Anything discovered in a prebuy that can be corrected by routine maintenance should not be considered a dealbreaker. Items affecting the safety of flight, or which are likely to lead to very expensive repairs in short order, certainly should. If your prebuy facility discovers that the aircraft is just not safe for flight, is likely to break the bank, or just isn't in the condition that the seller represents it to be in, just walk away!

(6) A Prebuy Should Address The Most Expensive Squawks First

Why spend a ton of cash having the shop of your choice make a long list of minor discrepancies, only to find a dealbreaker later on? A good prebuy looks for the most serious issues first. The examination should start with the expensive parts -- only after known major potential problem areas have been ruled out should the mechanic delve more deeply. If the shop finds a major issue early on, you don't have to continue with the prebuy -- just walk away!

(7) A Prebuy Should Be Performed In Phases

In the interest of minimizing your investment in a candidate aircraft, AvSport breaks its prebuy examinations into three phases:

  1. Documentation
  2. Powerplant
  3. Airframe

Phase 1 is generally performed before the aircraft is even delivered to the prebuy facility. The seller typically emails PDF scans of the airframe, engine, and propeller logbooks, along with the aircraft's equipment list, weight and balance documents, service bulletin compliance records, and any Letters of Authorization issued by the manufacturer. During this phase, your prebuy representative will start gathering information about the use history of the aircraft: where it was based (coastal region vs. inland), where it was stored (hangar or tiedown), how it was used (flight training or personal transportation), how many hours a year it was flown, frequency of oil changes, types of operating fluids used, etc. You should already have obtained the FAA data disk for any plane you are considering (it only costs $10, and contains such valuable information as the plane's ownership and registration history, any liens recorded against it, any reportable accidents, etc.), and will provide this to your prebuy mechanic for review. A thorough examination of these documents (which generally takes about half a day) may possibly find significant discrepancies, in which case you will probably want to walk away! Barring this, you are free to proceed on to Phase 2.

Because engine failure can be both extremely costly and potentially hazardous, if the aircraft documentation is in order, it makes sense to examine the engine and prop next. This is idealy done in the mechanic's shop, takes about half a day, and usually starts with an engine warmup and runup, followed by a compression check while the engine is still hot. Sparkplugs are generally pulled and examined, the oil sampled, an oil filter may possibly be cut open in a search for metallic contamination, and the insides of the cylinders may be viewed with a borescope. Although even a thorough engine examination is no guarantee that the engine will continue running well to TBO, any serious issues uncovered here may be a good reason to walk away!

If things look good ahead of the firewall, Phase 3 will examine the airframe for corrosion, the wing attach mechanisms and landing gear for security, and the flight controls for proper attachment, correct function, and absence of excessive wear. This is also a half-day process, and if no major concerns are uncovered, you may then decide to proceed with the purchase of your aircraft. But, if there are structural issues uncovered in the airframe examination that can't be readily corrected with routine maintenance, don't be afraid to walk away!

Here is a sample Prebuy Examination checklist. The aviation maintenance technician can make notes and record comments on the line next to each item, and return this form to the prospective buyer as his or her formal report. We can't speak for other shops, but for an LSA prebuy examination, AvSport charges a flat $200 labor rate for each phase initiated (plus, of course, the cost of any parts and consumables used). As the customer, you are free to discontinue the process at any time a red flag is encountered, paying only for the phases of the examination actually undertaken.

(8) A Prebuy Should Include A Search For Modifications

FAA and ASTM rules require that, in the case of a Special Light Sport Aircraft (SLSA), any aircraft modifications and equipment changes require a Letter of Authorization (LoA) from the airframe manufacturer. Too often, previous owners perform undocumented and unauthorized modifications. During Phase 1 of a prebuy, we look for LoAs in the aircraft documents. During Phases 2 and 3, we look for modifications for which no LoA is evident. If such modifications are present and no LoA has been obtained, no shop or mechanic can legally return your aircraft to service following a Condition Inspection. During a prebuy on an SLSA, should we happen to detect modifications for which no LoA has been issued, be prepared to walk away!

(9) Your Prebuy Examiner Is Not A Purchasing Agent

The mechanic's job is to give you an honest and independent assessment of just what it is you're buying. He or she is not there to negotiate on your behalf with the seller; that's your job! Before this process even begins, you will have made your best deal with the seller (or, at least, you will have made a conditional offer, which the seller has accepted). The prebuy shop will present you with a detailed report of its findings. Since the mechanic is working for you, this information will not normally be released to the seller, unless you so authorize. Armed with this report, you may choose to bargain with the seller to either lower the price, or to correct discrepancies at the seller's expense. More often than not, however, the result of a prebuy is a binary function -- you will either go ahead with the purchase at the previously agreed price, or you will walk away. In neither case should you expect your mechanic to intercede with the seller in any way -- that's just not his or her job.

(10) You Now Have A Qualified Mechanic

If you decide to go through with the purchase of this particular aircraft, congratulations! Fly it safely and frequently, and above all else, have fun. Should you require maintenance or service during your years of happy aircraft ownership, you have now established a relationship with a shop that has some familiarity with your particular machine. This familiarity should save you some money downstream, and will give you some peace of mind throughout the entire ownership and flying experience. Safe skies!

(11) Relevant EAA Webinars:

(12) Acknowledgment:

Much of what I know about prebuy examinations I learned from Mike Busch, A&P/AI, founder and CEO of Savvy Aircraft Maintenance Management. I have incorporated many of Mike's recommendations into this document. I am grateful to Mike for so willingly sharing his extensive knowledge and experience with his fellow EAA members.

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Contact Prof. Shuch
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This page last updated 27 June 2015
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