Bits and Pieces
Aircraft Inspection Techniques for Homebuilders
By Bill Evans, President - EAA Chapter 266, EAA 794228
This series of articles is for homebuilders, and it began as a PowerPoint presentation, which in turn began with two very different aircraft accidents involving homebuilts. I had friends who knew the owner pilots of these airplanes. Bob Curtis of Sun 'n Fun International Fly-In & Expo at Lakeland, Florida, said, "If you do a forum, pick a topic you know something about." Those accidents made the decision an easy one.
Aircraft inspection is what I did for a lifetime, but I also turned wrenches, taught type endorsement courses, and worked as a technical writer, hence this article. So that explains two things: who I am and why I'm launching this series of articles in Bits and Pieces. Actually this installment is mostly an introduction to inspection. But as you'll see, an introduction is necessary.
Inspection is defined as "the comparison of anything to a known standard". A comprehensive inspection removes a great deal of uncertainty about whether an aircraft is safe to fly. Your goal is to ensure that every time you take off, your aircraft and occupants will land safely.
While your eyes are the primary sense used, you will also use sound, touch, and even smell; leaks and rotten wood have smells.
Inspection often involves specialized equipment. It may not all be expensive, but some equipment will be necessary.
Roles: Who Are You?
When you build and own an aircraft, you are also the pilot, mechanic, and right now, the inspector.
Your job as an inspector is to inspect everything on the aircraft - everything! The most serious accusation that can be brought against you is that your inspection was not thorough or adequate.
- Defect importance - There will be a time for that, but that time is not now. Inspect and record!
- Options - A comprehensive inspection will provide you with options for future maintenance. It will give you the opportunity to record everything you find.
- Time - Consistency degrades with time. You will stop recording defects if you find the same defect in 20 places. Using gauges helps to prevent degradation of your standard.
- Tasks - If you become tired of checking spar rivets, record what you have inspected and change tasks. Because you have a record, you can come back to that spar.
Chain of events: Just as accidents are a chain of events, so are defects. (The Canadian term for defects is snags, which is what we'll call them.)
You are inspecting your homebuilt, and you see, hear, feel, smell something you don't remember finding before.
Stop! This is the first principle of inspection. If you find a snag, stop and ask yourself, "Where exactly in the chain of events does this snag fit in?"
- Origination? It all began here.
- Subsequent failure due to loads transferring - If a part breaks, the loads causing that break have shifted elsewhere. The loads did not just go away. Where are those loads now? They are working on a part never designed to take those loads in the first place. Find that part or those parts.
- Tertiary failure: Is this snag a peripheral fault only indirectly connected to the primary defect?
- Endgame: Is this snag the end of a chain of events?
Inspector: Find them all!
Inspection is a very different skill set, with different tools than the homebuilder, mechanic, pilot, or owner would normally exercise.
There are many homebuilders who choose to have an AME inspect their aircraft rather than inspect it themselves. There is a reason for that; inspection requires a unique skill set. You will find that here in the months ahead, and you will be able to assess your own capabilities.
If there is a snag on your aircraft that could take your life, the very first person who should know about it is you. In this little series we will often be considering things that could take your life, to find them before they find you.
As an inspector you will think, inspect, and prioritize differently than the owner, pilot, or mechanic. This series was written to allow you to acquire that way of thinking, and to have the tools, documents, and processes that support your new way of thinking. When you see the bank for an airplane loan, fly your aircraft, or service your aircraft, you may wear different hats. As an inspector you really will wear a different hat!
Having been inspecting for about 30 years, my employer sent all the inspectors on an inspection course. It lasted a week. The result was an adapted version of the air regulations, mandated by the Dubbin Commission after the Gimli Glider event - the 767 which ran out of fuel and landed successfully at the ex-BCATP training airport of Gimli, Manitoba. At no time did the two instructors teach the class how to inspect an aircraft!
This series will teach you nothing about air regulations. It is very difficult to find anything that will teach you how to inspect an aircraft, never mind a homebuilt, and that is the purpose of this series.
In future articles we will discuss:
- inspection documents
- sequence of tasks
- principles of inspection
- prepare yourself, inspector - human factors
- inspection equipment
- types of structures and techniques
- corrosion and aging aircraft
- dealing with snags - job cards
- logbook entries