SECTION 15 FINAL INSPECTION AND FLIGHT TEST
RV AIRCRAFT
15-1
SEC 15r8 12/23/10
In the life of every homebuilder there comes the day when his airplane is finished and ready to fly.
Or is it?
For some builders the process has been long, sometimes several years. We learn from experience and we pass that
learning along to our builders as needed. Before you undertake the test flying of your new airplane, check for
“Service Bulletins”
on our web site at
www.vansaircraft.com
. It is in your best interest to check this web site peri-
odically to keep up with the latest improvements in your aircraft.
A reported 20% to 30% of homebuilt aircraft fatal accidents occur within the flight test phase (first 25-40 hrs.). Flight
test statistics for RVs are far safer than this. However, these sobering statistics should provide the incentive to under-
take flight testing in the most professional manner possible. Because the majority of accidents, perhaps 80-90%,
result from pilot error, pilot “airworthiness” should be of paramount concern.
The last steps in building an airplane are a very thorough final inspection of both the pilot and the aircraft to assure
that everything possible has been done to make it airworthy, followed by a carefully planned and organized flight test
program to verify that the airplane not only flies, but meets all performance, stability, and handling goals.
One who builds a homebuilt airplane is known as an “amateur builder”. However, we don’t often use the term
“amateur test pilot” to define his role during the flight testing of an airplane. In reality, the typical private pilot is terribly
under-qualified to serve as a test pilot, at least when contrasted to the training and qualification of professional test
pilots. Fortunately, the flight testing of many ABE (Amateur Built Experimental) aircraft consists of little more than a
self help check out in a new airplane. Aircraft of proven design (such as the RVs), which have been accurately built
from high quality kits, usually pose few challenges to their test pilots, even in the early hours of flight. However, this
ideal cannot be guaranteed and no assumptions of unquestionable airworthiness should be made. A “test” pilot must
be prepared for any irregularity which may occur.
The goal of this chapter is to help you do flight test planning and flight testing in a way that eliminates the need for you
to demonstrate that you have the “right stuff”. When it comes to flight testing, boredom beats excitement. This chap-
ter will also help you gain a better knowledge of the fine points of the performance, stability, and handling qualities of
your airplane. Put another way, we will try to teach you some of the things which test pilots need to know.
Using the first flight of your RV as the central point, we can consider two basic phases of testing: Pre-First Flight and
Post First Flight.
PRE FIRST FLIGHT
Pre-First Flight activities include two main topics; inspection and preparation of the aircraft, and inspection and prepa-
ration of the pilot. Everyone agrees that the aircraft should be thoroughly checked over and made airworthy, but not
everyone is as concerned about the airmanship of the pilot, particularly the pilot himself. They should be. After the
first flight is completed, subsequent flights can be dedicated to increasing the proficiency of the pilot, improving his or
her connection to the airplane, and exploring the performance and limits of the airplane itself.
The following sequence of inspection, preparation and flight test procedures has been compiled from a series of flight
test articles authored by Tony Bingelis in the Jan-Mar. 1989 issues of
Sport Aviation,
a 1989 FAA Advisory Circular
titled
Amateur-built Aircraft Flight Testing Handbook
, and insights from RV designer Richard VanGrunsven. Another
more in depth and very valuable book is
Flight Testing Homebuilt Aircraft
by Vaughn Askew, published by the Iowa
State University Press, and also available from Van’s Aircraft.
INSPECTION AND PREPARATION OF THE AIRFRAME
Weight and Balance:
Go over your figures one more time. How will the airplane be loaded for test flight? Will it be
under gross? Don't fly the airplane with an aft CG condition. If necessary, add ballast and fasten it securely. Be sure
the ballast will not interfere with the controls, or chafe on installed wiring and fuel lines. Carry plenty of fuel for the first
flight, but limit it to no more than half your fuel supply.
Landing Gear:
For RV-8 builders, assure compliance with the wheel alignment specification presented in Section
10 of this manual. If a tailwheel is installed, examine it to see that its pivot axis is vertical, or, preferably, slopes back
slightly (trails.) Difficult runway handling often results when the tail wheel pivot axis is raked forward and the tire con-
tacts the ground ahead of the imaginary projected pivot axis.
SECTION 15. FINAL INSPECTION AND
FLIGHT TEST
SECTION 15 FINAL INSPECTION AND FLIGHT TEST
RV AIRCRAFT
15-2
SEC 15r8 12/23/10
Be sure the linkage and springs on a steerable tailwheel are correctly tensioned. There should be between 1/4'' and
1/2'' sag in the chain/cable assembly.
Brake System:
Check for positive pressure at the brake pedals. Both should have similar feel; a firm resistance after
about 1/2'' of pedal travel. The pressure should hold as long the foot pressure is held on the pedal. While holding the
brakes, have someone try to push or pull the plane to make sure that the brakes are working. “Soft” pedals usually
indicate the presence of air in the brake lines, require the system to be purged. Pedals that “bleed” down and need
to be “pumped” up often indicate a fluid leak in the lines, master cylinder, or brake cylinder itself.
Flap Operation:
Check the flap system through its full travel for freedom of movement. On manual flaps, have
someone apply lifting pressure to the flap itself while you operate the flap handle to make sure the latch mechanism
holds and releases as it should. Check to assure that the flap handle and/or flaps have travel limits and cannot be
extended beyond the maximum intended position, causing an over-center binding.
Flight Controls:
Your control system is vital to safe flight and requires very close scrutiny. Operate the rudder, ele-
vator, and aileron controls through their full travel. Assure yourself that ALL the controls are connected, secured and
safetied -- and that they all operate freely and smoothly and in the correct direction. No play should be permitted in
the control hinges; sloppiness may induce flutter. Likewise the trim tabs must be free of excessive play. Review the
control travel limits.
Fuel System:
Check your fuel se-
lector valve. Perform tests to assure
that the tank indicated is actually
feeding, and that the “off” position
does stop the fuel flow. It must func-
tion easily with a definite click in
each tank position. Verify that the
engine will run in each tank position
(except OFF, of course.) Smell fuel
in the cockpit? Check the connec-
tions for each fuel line. A fuel leak
cannot be tolerated.
Are your vent lines open (are you sure?) and properly exited outside the aircraft? Protect the vent openings with alu-
minum screen to keep the bugs out.
Propeller:
Re-torque and re-safety the propeller bolts -- especially if a wood prop is installed. Recheck the track of
the propeller to make sure the blades are rotating in the same plane. An easy procedure that should take about thirty
minutes is shown in Section 12.
An out-of-track propeller condition can be corrected by placing a paper shim between the rear face of the prop and
the mounting flange, on the side with the trailing tip. Common typing or copier paper can be used for the shim,. By
loosening the prop bolts, a paper shim can be slipped in and the bolts re-torqued with a minimum effort. A single
sheet thickness of copier paper is equal to a tip correction of about 1/16”. After shimming, re-check for track. Repeat
this process until the prop blades track within 1/16”.
Propeller Shaft Extension Alignment:
A less common but more serious problem than prop tracking is that of
crankshaft prop flange misalignment. If the crankshaft flange is bent slightly, it would cause an out-of-track prop con-
dition, if a prop were bolted directly to it without an extension. When a shaft extension is used, the prop becomes not
only out of track, but off center as well. If this condition goes undetected, a serious vibration (out-of-balance)condition
can result, even though the prop is balanced and in track.
Checking for an out-of-alignment flange and prop shaft extension is done with a dial indicator. Aircraft mechanics
and machinists are familiar with this tool, and can probably help you with this test.
The dial indicator mounting stand (shaft) must be clamped to the engine and positioned so that its sensor tip is in
contact with the front flange of the prop extension. Rotating the prop through 360 degrees will indicate an out of line
condition. The prop extension can be shimmed straight using the same technique as for prop tracking.
Engine Controls:
Verify direction of movement and security of attachment at the engine. This means somebody
needs to check the movement at the carburetor -- takes two people to do it. Beware of possible spring-back or inad-
vertent locking in the linkage when any engine control is moved to its extreme position.
Checklists and placards: No excuses, you need them. Review them for accuracy, completeness, and ready access.
One pre-takeoff check list that is easy to remember is based on the letters in the word C I G A R E T T E. They stand
for:
x
Controls:
Move and visually check for proper operation.
x
Instruments:
Check functioning of oil pressure, fuel pressure, tachometer, MP, and any other instruments
which are in operation prior to flight.
Design Travel in degrees
Maximum Up/Down
Minimum Up/Down
Elevator
30/25
25/20
Aileron
32/17
25/15
Rudder
35/35 l/r
30/30 l/r
Flaps
40
45
(32
37 RV-9/9A)
Trim Tab
25
35
