At this point you’ve found an affordable plane that meets your mission. Your logbook review was satisfactory, and a document search hasn’t found anything unsettling. On paper, this is the plane you should buy. Before getting too excited, however, remember the “on paper” part of that. There could be any number of things wrong with the plane that kill the deal. The pre-buy evaluation is one arm of your defense against problems that don’t appear in the logbook; the test flight is the other.

The test flight is your opportunity to experience what owning the plane will be like. It’s your opportunity to test every part of the plane, and asses its subjective quality. It’s common for non-critical components to gradually decay and break, especially if the owner has been planning to sell for some time. Also, not every plane handles the same. It’s possible for a plane to be perfectly safe yet have rough handling on the ground, INOP avionics, annoying feedback on the intercom, and so on. A pre-buy evaluation from an A&P won’t catch things like that so you need to catch them in the test flight.

Doing a thorough test flight is tricky because it will probably be a short, day VFR flight near an airport, but most of your flying will probably be longer cross countries, possibly on an IFR flight plan, possibly with passengers. This means it’s easy to overlook things you wouldn’t normally use on a local flight plan like navigation equipment, lights, and rear headset plugs. In order to do a good test flight, you need to prepare a checklist beforehand. A reasonable starting point:

• Lights:
  • beacon, strobes, landing/taxi light, nav lights
  • interior lights
  • panel lights
  • instrument illumination
• Handling:
  • turns, climbs, descents
  • slow flight
  • stalls
• Avoinics
  • GPS
  • Traffic
  • Satellite Weather
  • Strikefinder/Stormscope
  • COM1/COM2
  • VOR1/VOR2
  • ILS1/ILS2
  • Each intercom place
  • Cabin speaker
• Engine: cross check gauge numbers with POH in all phases of flight
• Interior: quality, comfort, condition

Start from that list, and expand it with other items that are important to you or unique to the aircraft. If possible, bring a friend or spouse that will fly often with you. Give them a copy of your checklist, and highlight everything that they can evaluate. Make sure they know what they’re looking for, and give them paper + pen to take notes. As a pilot, your focus will be on things in the panel and engine compartment, making it easy for you to overlook things that passengers care about like noise levels and seat comfort (especially in the back seat).

Don’t fret too much about finding every single thing. The main purpose is to determine whether the plane is unacceptable, and find anything you can use to help in the negotiation. Inevitably, you will miss things that need to be repaired later. That’s OK! Things break on planes; that’s why you maintain a maintenance reserve. Whether small things break shortly before or or after you buy the plane doesn’t make a huge difference.