Transcript Document
Building a Sophisticated Aircraft
Presented by Kas Osterbuhr ([email protected])
The primary goal is motivation:
Your project can easily overwhelm you if your attitude isn’t positive. Visualize your high speed flyby when flight testing is complete, or your perfect IFR approach relying on the instruments you have installed in the aircraft.
Organize your project…
Maintain folders that are organized and indexed so information is always in the same place and easily referenced. The Joint Aircraft System/Component (JASC) codes are helpful.
Keep your shop clean and orderly. One minute spent looking for something throughout the day will eventually rob you of productivity.
…your work area, and your parts
Think like an airplane…
It is not quite as hard as you may believe. Airplanes are machines like any other, they have controls and levers, inputs and outputs.
When you do, think fast. You could put your head in a plastic bag for a couple minutes and stand outside in a snowstorm to make things a little more realistic.
…and then think like a human
Consider human factors…
Keep your manuals up to date with revisions and annotations. Keep notes about quirky systems so that someone else (or you in one year) won’t have to reinvent the wheel.
Clean parts, clean design, and modular sub-assemblies will make your mechanic drool.
This door, for example was designed to eliminate pilot error. It only provides power to the door seal pump when both latches are closed. If either latch is ajar, an annunciator will illuminate. It only required two microswitches and three wires.
…for both pilot and mechanic
Study your aircraft…
Most aircraft take a long time to build. In four years, your avionics may be outdated or worse, dead! Wait until the end if possible to integrate the electrical systems. When you do, make sure you fully understand the functions they can offer you. It is worth studying the manuals to understand the way your systems really operate. There may be a really handy switch you can install that makes your moving map easier to use in flight.
…there is always more to learn
Visualize and plan systems…
TCAD Intercom Fuel Pump Weather Hydraulic Fluid Rubber Hoses Tefzel Wiring Soldered Joints Aluminum Carbon Lightning Epoxy Adhesives Lexan Temperature Altitude Decompression Pressurization Humidity Shock Crash Safety Explosion Vibration Waterproofness Sands and Dust Magnetic Effect Power Input
…it is a complex web to weave
FMEA, what is it?
Failure mode and effects analysis is a simple tool developed to solve the problem of “what if.” It’s beginning actually came from the aerospace industry. There are numerous ways to approach FMEA. This is just one of them.
RISK PRIORITY NUMBER (RPN) A failure that can NOT be detected, can’t be remedied, happens often and is severe in nature is the ultimate risk.
A failure that is easy to see and fix, never happens and has almost no consequence is something to be disregarded.
Failure Severity
crack and failure of pin A32 loss of electrical power not overcentering door out of fuel primary vacuum pump door departs aircraft aircraft glides to land switch to backup only vac pump in IFR reduced instruments
Detectibility
8 not detectable 10
Frequency
10 annunciator 5 fuel flow, qty 5 average life 1 3 5 9 average life 5 1 5 1 3
RPN
80 50 15 75 3 135 In a Lancair IV-P: If the overboard vent on this fuel pump were exposed to cabin pressure (i.e. not installed by the builder as dictated by the plans), AND the fuel pump had a bad seal, AND the pilot didn’t do a full power and pressurized run-up prior to takeoff to detect the problem, AND the pilot departed with the cabin pressurization controls set to pressurize –
the result would be a dead engine about 60 seconds after applying power
.
…it helps you think ‘failure’
Humble beginnings…
Firewall forward is always a challenge. High heat and vibration as well as exposure to fluids (oil and fuel) are key concerns for anything in the engine compartment. Common problems are improper termination of hoses and ducting and chafing/interference issues. Always have as much information as soon as you can have it to avoid re-engineering your work.
Systems integration presents the greatest obstacle for the average builder. By the time you’ve spent 4 years building the perfect airframe, there seems little time left for details such as using the proper crimp tool, or adel clamping a wire bundle instead of using nylon ties. The later stages of a project are always emotional and tend to get rushed. Your experience is not to be abused at this point. Take advantage of your time on the ground, when you’re in the air it will be worth it.
…build a good foundation
The work of a craftsman…
You will be rewarded for your time spent with the details. Labeling fluid lines for example can make an instantaneous difference in the quality of your aircraft. It raises the bar and encourages you to continue with other innovative methods of systems installation.
…success motivates success
Keep track of the chaos…
Microsoft Excel or another spreadsheet program can turn confusing avionics and electronics into a simple to understand network of pins, wires and connectors. It is very valuable to catalog this information starting as soon as you begin building your aircraft.
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…work smarter, not harder
Document like the pros…
Keep a drawing of your systems with a current revision date on the drawing and a list of the changes. Don’t discard old information because it may be helpful in remembering why you changed something. Use copies of diagrams for example to highlight wires as you install them.
Why is it not a good idea to do stalls at FL200 in a Lancair IV-P? What on earth does the hydraulic pump have to do with the flap indicator? There will be questions, no matter how well you know your aircraft, that you may forget the answer to. Over time you will not recall everything as clearly as when you designed the plane, so keep track!
…it’s not amateur built!
Parts, parts, parts…
Get lots of hardware and treat it like a consumable, because it is. Parts and materials are cheap in the long run. Cut everything five feet longer than you think you need, buy a few extra of everything. Coming up short is very costly.
Do not try to do a job without the right tool. It will cost you a lot of time and money in the end. Sure that crimp may hold for now, but give it 200 hours of vibration and see what loosing an alternator in flight does for you.
…tools, tools, tools
There is more out there…
No matter how good you are, you can always get better. You can learn something from everyone. Building a 350mph, pressurized aircraft capable of flying from A to B with the windows painted black is not an easy task. Think responsibly when you are building your aircraft. Learn everything you can about every aspect of your aircraft.
Do some research and poke around on the internet. You’ll find parts suppliers with some really trick hardware. Don’t be afraid to call people and ask for product catalogs. Companies have spent millions of dollars solving the same problems that you are facing right now, and usually they are really good at what they do.
…look around, pay attention
Think about safety…
This was not a smart move. Razorblade score marks like this may seem innocent enough but they could cost you your aircraft or your life. Give all of your work the inspection it deserves, with fresh eyes when possible. There is one very important concept in aviation to follow: take your time and do the job right the first time. Don’t compromise by letting “so-so” go. Would you let a pilot rated best friend take your family for a ride in the aircraft you just built, while you watched from the ground?
The A&P textbooks used to educate most mechanics have great information for homebuilders. Also, research service bulletins and airworthiness directives for your engine, airframe, avionics and accessories.