Tri City Aero Maintenance Inc.
Cirrus, Diamond, Mooney Factory Authorized Service Centre
 

 

 

PRE-PURCHASE INSPECTION

 
The Who, What, Why, When, Where and How

Who: 
Who needs one?

Anyone considering the purchase of a used airplane should have a pre-purchase inspection completed.  As airplanes trade owners and their age increases, the need for a pre-purchase inspection is of far greater importance.  If you are purchasing a virtually new airplane the process is of no less importance but should in effect be shorter.  However, most people are purchasing older used airplanes.  Many 40 year old planes are for sale and are still good buys.

Who should do it?

You should retain the services of a professional, either an AME or a Maintenance shop, to do the inspection.  Some shops prefer not to do these inspections for fear of being blamed for missing something, but are willing to help you after you have purchased the airplane.  If you can't trust each other before you buy how, will you trust each other after?  

What:

The pre-purchase inspection is to verify the airworthiness and general condition of the airplane, its engine, propeller and all installed systems and equipment for the prospective owner.  The person you retain, whether an AME or Maintenance shop, is working for YOU!   Some owners or prospective owners choose to become involved, while others do not.  In either case the work required is the same, it's just a matter of who is doing it. Many savvy owners can be a wealth of information on a particular airplane.  Ask your shop if you can be involved.  An educated consumer is the best consumer.

Why:

In the past this inspection was a mere formality, after all the fleet was young and airplanes were generally in good condition.  The AME would open the engine cowlings, check the cylinder compression and possibly remove and examine the oil filter for signs of engine troubles.  Following this was a basic walking inspection of the airplane, and a brief review of the log books.  This was usually followed by a nod of approval.

Sometimes only a few hours were spent on the entire process.  Even today some people believe that the process should only take a few hours, when in reality the process could involve days of work depending on the complexity of the airplane.  Times have changed. Airplanes are now expensive investments, in some cases with values equal to or greater than one's home.  Over the years the inspection process has become much more involved.

When:

Once you have narrowed down your search and selected an airplane, you should obtain pictures of the interior, exterior and instrument panel, followed by your personal inspection of the plane.  There is no sense bringing your AME to the airplane or airplane to him if you are not satisfied with the cosmetics of the plane. 

Where:

Although not always practical, the inspection should take place in your AME's hangar.  When working in his own shop the inspection quality should be better: his own tools, manual, equipment, telephone and internet are available as required.  In many cases it is more cost effective for you to pay the fuel expense of relocating the airplane, than it is to relocate the AME.  In those cases where the distances are too great, you and your AME will be traveling.  Be prepared for airfare, hotel, food and rental car expenses on top of the daily rate for the AME, as well as possibly renting shop space and tools while away.

How:

Accident History:

Once satisfied with the cosmetics of the airplane, the inspection process may begin.  First off is damage history. Lots of airplane advertisements list NDH (No Damage History) or now the updated version NKDH (No Known Damage History).  This is a handy catch phrase to let people off the hook for damage that may be revealed during the inspection.

Several resources are available to help with confirmation of this claim.  If you are purchasing an airplane from the USA you can search the NTSB web site http://www.ntsb.gov/NTSB/Query.asp using the registration marks to find any reported accidents.  This however is not a 100% guarantee. The FAA knows a lot about most airplanes, but not everything about every airplane is reported to them. The same holds true for Transport Canada.  In Canada you can search the CADORS web site http://www.tc.gc.ca/Aviation/applications/cadors/English/main.asp  to see if there are any reported accidents or incidents involving the airplane.   An accident history or damage history is not always a reason to abandon the particular airplane; it is one of many factors to consider.  As the fleet ages, finding that cream puff airplane is more challenging.

Sometimes just entering the airplane registration marks into an internet search engine reveals interesting things about an airplane.

Log Books and Technical History:

The vendor should be able provide the serial number for the airframe, as well as make, model and serial numbers for the engine and propeller as well as a list of all installed equipment, radios etc.  This information should now be compared to the Type Certificate Data Sheets for this particular model available at: http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/MainFrame?OpenFrameSet

Records of Airworthiness directive compliance, service bulletins and letters, modifications completed by STC (Supplemental Type Certificate) available at http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgstc.nsf/MainFrame?OpenFrameSet or "One time" approvals should be available.  Note that "One time" foreign approvals are not acceptable in Canada.  Note that not all maintenance shops have Service bulletins for all airframes.  Some manufacturers have some of their bulletins on line, Mooney for example has all of theirs on line available to everyone.

Airworthiness directives are mandatory and should be checked for compliance, both in the log books and by physical inspection of the aircraft.  In some cases airworthiness directives are signed off as being complied with, when they may not be.  Some airworthiness directives are very complex and can contain many parts. 

You can use the Transport Canada web site   http://www.tc.gc.ca/aviation/applications/cawis-swimn/awd-lv-cs1401.asp?rand to verify compliance.

When all these items check out, you can move on to the log books or technical history for the airplane.  Many owners now scan their logs to a computer and can send them electronically.  At this point an interested purchaser, as well as the AME, should review the records.  Hopefully the records begin when the plane was new at the factory and continue through to present.  Unfortunately this is not always the case.  Many have missing records, early logs are not passed on to new owners, maintenance shops lose them, and hangar fires have claimed some.  Some are "Lost" for other reasons in attempts to hide un-favourable history. 

In any case all available logs should be read from cover to cover.  Notes should be made as to dates and times of repairs, modifications, Airworthiness directive compliance, service bulletin and service letter compliance.  Hour meter replacements should be noted to help in calculating the real total time on the airplane.

While carrying out the review, look for patterns of continuity.  Did several years go by with no recorded activity at all?  If so why?  Was the engine preserved during this time?

Note the dates and times for engine and propeller overhaul, record these for calculating actual times on the components.  This is useful information.  I once carried out a pre-purchase on a Cessna 150 with very low total time, only to discover that the propeller had been exchanged for one with almost 10,000 hours!  This propeller had not been to an overhaul shop for many years. The likelihood of it failing at overhaul was quite high.  In Canada, a fixed pitch propeller requires a corrosion inspection every 5 years, while most constant speed propellers require a 10 year overhaul.

When was the last pitot static, transponder and altimeter system check completed?  In Canada and the USA it is required each 24 months.  What type of ELT is installed?  Is it approved in Canada?  Is it 406 MHz?  This item alone is quit costly and is required in Canada with change of ownership.  Was the tachometer accuracy check completed?  Tolerance is +/- 4%.  Was the compass swung in the last year?
 
Flight test:

With the review of the technical history complete, you can move on to the flight test of the airplane and its systems.  With the owner flying, have him or her demonstrate all systems for correct function, making notes on faults as the flight progresses.  Do the radios work correctly, both communication and navigation?   Ask to hand fly the plane yourself, does it fly wings level and ball centred?  Do the controls feel correct and smooth?  Engage the autopilot, does it function in all modes?  Is the engine smooth or does it vibrate?  Many have a "Sweet spot" while others have restricted power ranges.   Slow the airplane down and raise and lower the landing gear, does the motor make unusual sounds?  All systems should be functional other than those revealed in the sales agreement. 

Note any unusual odours in the cabin: fuel, exhaust, dead mouse odour, etc. both on the ground and in the air.  My hangar cat enjoys doing his own "Cat scan" and has found mice and birds both dead and alive in more than one airplane!

Physical Inspection:

With the flight test completed and satisfactory, the physical inspection can begin.  Here, there is great debate as to the depth of inspection required.   Some prefer an "Annual Inspection" check list.  I use the airframe manufacturer's inspection check list as well as one we have developed in the shop.  No matter what method is used, thorough, very thorough should be the requirement.  Airplane ownership has its share of surprises, the goal is to minimize them as much as possible.

There is no correct starting point.  I start with an examination of the data plates and the serial numbers, these items should match those in the log books.  There is no sense in continuing the inspection if there is a discrepancy or a missing data plate. 

I then move on to a walk around inspection of the airplane making notes on the exterior of the airplane.  A keen eye can spot many defects just on a simple walk around.  Next I move on to the engine as it is one of the single most expensive systems in the airplane.  Remove the cowls and carry out a cylinder compression test while the engine is still hot, drain the oil and cut open the oil filter or screen for examination. Using the check list as a guide, inspect the engine and propeller and all of the sub-systems noting all defects as you go.    

With the engine inspected it is now time to inspect the airframe.  At this point I turn on all of the systems to check for correct function, lights, stall vane, pitot heat etc. Make notes on items which don't work. 

Remove all of the inspection covers and fairings for a thorough inspection.  Look for signs of internal damage or repair.  Unusual rivet patterns or a change in the type of rivet are signs of a repair, as are drill shavings left in a wing.  If these are found, do they match the log books?   Look for signs of corrosion in the airframe as well.  Make notes as you proceed.

Inspect all of the flight control surfaces for damage and correct travel.  The Type Certificate specifies the correct travel limits as does the maintenance manual.  Inspect the control systems for worn or corroded cables, worn rod end bearings, etc.

Examine the windows for signs of cracks or damage. Compare these to the manufacturer's maintenance manual. Chemical burns from paint stripper are common, as are chips in pressurized windows.

Has the airplane been repainted?  If so were the flight controls re-balanced before installation?  Was the aircraft re-weighed with the painting?  It is not required but it is a good idea.  Has the interior fabric been replaced?  Were the materials approved?  Is there flammability certification for the material?

If it is a retractable landing gear airplane, raise it up on jacks for a landing gear inspection.  Is the gear worn and sloppy, cracked, rusting, etc?  Do the warning lights and position lights function?  How about the warning horn and anti retraction system?  Inspect the tires, brake discs and brake lining for wear below manufacturer's limits.  

Finalizing the deal:

With the inspection completed and a defect list in hand, now is the time to finalize the deal.  Depending on the purchase agreement, the vendor usually pays for the correction of airworthiness defects.  This can be in the form of adjusting the purchase price accordingly or paying for the repairs.  Non-airworthiness defects are at the discretion of the purchaser. 

In many cases, after the inspection and the repairs have been completed, an annual inspection can be signed off for the airplane.