Here's the scenario
You are presented with an opportunity to purchase an older plane 35-40% below market value. The catch is the airplane is an early nineties model and the logbooks are missing prior to the year 2005. Is the plane worth investigating, what should you pay, and what sorts of things should you be on the lookout for?
As a company which browses through (literally) hundreds of logbook pages, maintenance entries, etc. every day, we've seen a lot of different aircraft histories and found lots of interesting information scattered throughout the records. Information is pieced together from work orders, FAA 8130s, FAA 337s, invoices, maintenance entries, and more. The older the aircraft, the longer it takes for the true history of the airplane to manifest itself. Without these older records, it can be very difficult to ascertain a reliable picture of the aircraft and its maintenance history without calling up old maintenance shops and hoping that you a) remember which shops the airplane spent time at and b) that the maintenance shop still has maintenance records on file pertinent to your aircraft (if they're even still in business). Even the most experienced of owners will have to spend quite a bit of time rummaging through the logbooks to cover all the bases and, experienced or not, every airframe down to the serial number will have its nuances- not to mention the applicable airworthiness directives, service bulletins, etc.
So, first things first, assuming the aircraft even meets our criteria of serving up a 30-50% discount below market value for the maintenance records and also assuming you've done your homework and determined that this is the right airframe for your mission, let's cover some basic questions/pointers you should ask yourself.
Where will I get my pre-buy conducted? If we were to buy it, we would want a thorough pre-buy inspection, maybe two, conducted on the aircraft by an independent mechanic. Preferably, the inspection would be conducted by an elite mechanic for that airframe (every aircraft make/model has their gurus... do your homework!)
Pre-buy would need to include complete AD/SB compliance search, which will cost you time and money. Even if the aircraft has a recent AD/SB compliance report, it's still not a bad idea to get another conducted. During these compliance reports, mechanics will drill down into ADs and SBs all the way by serial number to figure out if the maintenance item has been complied with, when it was complied with, and how it was complied with.
Pre-buy should include a very thorough and likely invasive corrosion inspection.
Where has the aircraft spent the majority of its life? There are several parts to this question. Where the airplane lived reveals a couple things- owner's interest in the longevity of the aircraft, and likely exposure to corrosion.
Ok, so the records are missing prior to 2005, right? We would dig up the registration records that can be obtained from the FAA. After purchasing these docs, you will receive FAA 337s, registration documents, and other important airworthiness documents. From here, you can at least get some insight into the aircraft's past. Check the registration documents- in what states has the aircraft lived? Arizona is a drier and less corrosive environment than Florida. You can make subjective inferences from these documents. We would conservatively assume that the aircraft spent its days and nights outside, furthering the notion of why the aircraft needs to be priced under market value. You can always attempt to contact the previous registered owners to see if they remember keeping the aircraft inside or out, but for conservative purposes, you might as well just assume it was kept outside and exposed to the elements.
The 337s provided by the FAA are useful, but only insofar as they are accurate and complete. You cannot assume that the 337s you receive from the FAA are an accurate and complete representation of the actual 337s that were meant to be filed with them. The reason for this is sometimes mechanics might forget to send out the 337s or get it to the proper authorities, sometimes mail gets lost, etc. Regardless, we have counted dozens of situations where there are fewer records on file with the FAA than are contained in the aircraft's maintenance records. One the services we offer is a complete 337 cross-check where we compare what we find in your maintenance records to what the FAA has on file. It's a nice sanity check to have. There are some reasons why an aircraft's maintenance records may have more 337s in the records than the FAA has, but we leave it up to the owner to discuss with the mechanics.
How old are they engine and props? Were they manufactured prior to 2005? If the engine is older than 2005, and there aren't any engine records prior to 2005, use some caution (especially if you're planning on ferrying this airplane back to home base!). Again, erring on the side of conservatism, assume it sat for awhile, but some logical thoughts you might have could include:
You might be able to figure out when this make/model of engine was manufactured by contacting the engine manufacturer with the serial number- shedding at least a little more light on a possible install date (note: aircraft engines can sit in proper storage for some time after being manufactured so use the manufacture date as a conservative estimate).
If the engine did sit for awhile, is it worth just writing it off entirely and assuming I'll need an overhaul or factory remanufactured engine? Engines that don't fly consistently and often are far more subject to corrosion and other issues.
If you can somehow deduce through the records approximately what the total time on airframe (TTAF) was at install and what year it was installed in, perhaps you can take the current aircraft's TTAF minus the install TTAF and divide it by the number of years between now and the install date. This will give you a linear approximation of how many hours a year the aircraft was flown. The more the merrier. But, the best way to figure this out is to check the total time the aircraft flew between annuals.
What other maintenance items should I think about? There are a number (read "hundreds") of potential maintenance items you should be aware of, but here are a few pointers:
Assuming the aircraft has fuel bladders (e.g. it's not a "wet-wing" like the Cirrus models), and assuming there isn't a recent record of a fuel bladder replacement, assume you'll have to spend some money installing new bladders (this can be costly!).
On airplanes equipped with retractable gear, you'll want to know when the last time the landing gear motor was overhauled, when the last time the rod-ends were replaced, if the downspring tensions are correct, and much more. At the very least, and for your own safety, if the airplane hasn't flown much and the maintenance doesn't seem consistent, get the landing gear checked out by an A&P before going up for a demo flight. The last thing you want to deal with is a gear-up landing due to a maintenance problem during a demo flight... it's just ugly.
Any recent entries indicating that the control-cables were checked? On an older airplane, figure out when the last time they were replaced.
Is the owner advertising a recent paint job? Make sure you review the appropriate maintenance entries. The airplane should have had its control surfaces rebalanced as well as received a recent weight and balance entry.
... and the list goes on, but that's an OK start.
Was this current owner disciplined with their maintenance record keeping habits? Use the maintenance records to get a sense of the current owner's maintenance discipline. Was the aircraft a hangar queen or did it fly regularly? Did he/she keep up with regular oil changes? Were boroscope and compression checks performed at least annually? How about those sneaky FAR inspections? Often, it's not a bad idea to figure out what owner groups the owner is a part of and try to figure out whether or not he/she attended any annual aircraft seminars, engine management courses, etc. The more current and the more knowledgeable the better.
Messy and unorganized maintenance records can be a troubling sign- especially for an airplane already missing entries. Who knows what other entries didn't make it into the logs?
This brief list should help you get started with thinking about the various questions you should be asking yourself before purchasing an airplane with missing maintenance records. Obviously, the older the airplane, the more precarious the situation. Also, other factors come into play such as turbocharging, pressurization, etc. We're not saying you shouldn't ever buy an airplane with missing logbooks, but if you are an inexperienced owner certainly take advantage of all the resources you have at your disposal and remember that the costs of getting the airplane in shape can easily exceed even a 50% discount from market value. We here at PlaneLogiX are always happy to answer any questions you might have, and if you want to, you can take advantage of our pre-buy services where you and the current owner divide the cost of a transcription accordingly (typically, we recommend the owner paying for most of it as this service adds value to their airplane if you don't end up buying it). We'll do our best to answer those questions you see above, and more.
Fly smart. Fly safe. PlaneLogiX