6/29/15 Appendix 5 APPENDIX 5. HIGH-INERTIA AND/OR LOW-DRAG
1. DEFINITION. Airplanes that slowly decelerate when power is removed.
2. DISCUSSION.
a. Example Accident from the National Transportation Safety Board (NTSB) Records.
(1) Accident. The homebuilt airplane landed long and could not make a complete stop on the available runway; the airplane bounced three times. On the third bounce, the pilot lowered the tail wheel; the main landing gear came off the ground, indicating too much airspeed. He applied power to go around with 300 feet of runway remaining. To avoid trees, he pulled up abruptly, then pushed over again. The engine quit momentarily during the pushover (likely due to negative G Load), and the airplane crashed on a nearby golf course.
(2) Probable Cause. The pilot’s failure to maintain airspeed and his failure to perform a go-around. The pilot’s misjudgment of speed and distance during the landing is a contributing factor.
b. Inherent Risks/Hazards.
(1) As stated in Appendix 4, drag reduction was and still is a major objective in airplane design. These airplanes are on the leading edge of this design trait. They are beautiful, sleek, and even sitting on the ground just look fast. Airplanes in this family are generally fast, efficient, and may have significant range; however, the hazard is that unless managed, these airplanes can build excessive speed during critical flight phases such as approach and landing. The risks of unmanaged speed include overshooting final approach, inadvertent stalls, loss of control, wheel barrowing, and runway excursions.
(2) These risks are not inherent to only high-performance airplanes. For example, airplanes resembling motor gliders may experience substantial float and overshoot a substantial amount of runway with only a few knots of extra speed on landing. This family also includes airplanes designed for high-speed cruise. In some cases these airplanes have relatively high stall speed and, consequently, high approach and landing speeds. Airplanes with high landing speeds can be a challenge for pilots experienced only in type-certificated (TC) airplanes. High landing speed can easily translate to long touchdowns, runway overruns, and late go-around decisions.
Also challenging for pilots of these airplanes is following a slower airplane into the traffic pattern or a fly-in event such as AirVenture.
3. RECOMMENDED GROUND TRAINING. Pilots transitioning to this family of airplanes should spend some time reviewing the proper power, airspeed operating limits, altitude, and configuration for their specific airplane’s approach and landing. Discussion should include configuration and speed control for a stabilized descent and approach. Performance calculations for landing distance and safe margins for runway length should be done so pilots are aware of the runway lengths needed for safe operations. Decisionmaking on when to reject landings and go around should be made before flying.
6/29/15 Appendix 5
4. RECOMMENDED FLIGHT TRAINING. A thorough airplane check-out by a qualified instructor, preferably with recent experience in your airplane make and model, is always a good idea. Flight training should include descents from altitude, pattern work, and landing distance awareness. Practice descents to determine distance versus altitude to begin a proper descent profile. A properly planned descent should permit the aircraft to descend without large reductions in power and to avoid over-speeding the aircraft. If the airplane is equipped with speed brakes, incorporate them into the training. Pattern practice should emphasize proper power, altitude, and configuration for the approach and landing phase of flight. Demonstrate the landing distance required under various aircraft configurations and then practice for repeatability.
There needs to be an emphasis on control and understanding your airplane’s stopping distance.
6/29/15 Appendix 6 APPENDIX 6. NONTRADITIONAL CONFIGURATION AND/OR CONTROLS
1. DEFINITION. An airplane whose external configuration is sufficiently different from traditional type-certificated (TC) single-wing, empennage-mounted tail designs so that it displays nontraditional handling qualities. Flight control surfaces different from typical elevator-aileronrudder-engine/prop arrangements and/or flight control systems are different from typical stick/yoke-pedals implementations.
2. DISCUSSION.
a. External Configuration. TC’d airplanes follow a fairly standard external configuration.
There is usually one main wing, each with one aileron and possibly a flap, and a tail consisting of a vertical and horizontal stabilizer with trailing edge rudder and elevator. There can be slight variations such as a stabilator instead of a stabilizer and elevator, or a V-tail design that uses ruddervators to perform both yaw and pitch functions. Compliance with regulations ensures that regardless of the configuration, all TC’d airplanes behave in expected, intuitive, and acceptable ways.
b. Innovations. The experimental aircraft community has a long history of innovation, including nontraditional configuration and controls. Traditional wing/tail combinations are common, but so are canards and wing-mounted pushers. There might be flaperons performing double duty as roll controllers and high-lift devices leading edge slats, multiple lifting wings, differential spoilers, all-moving vertical tails, etc. In the cockpit, an experimental airplane might have a yoke or a stick, and that stick could be an outboard side-stick or one between two seats. It might pivot traditionally or translate/slide for pitch control while pivoting for roll control. Some experimental airplanes have the throttle on the pilot’s left, some on the right, and some have both, leaving the option of which hand to use to the pilot. There are even some with the throttle on the floor between the pilot’s legs. The hazard is that such variety of cockpit control locations and operation can lead to potential misuse of the controls due to the unfamiliar human-machine interface.
c. Canards.
(1) Canards are very popular in the experimental airplane world. While they offer several aerodynamic advantages, they also carry unique risks. Since both the canard and wing lift upward, this is a more aerodynamically efficient design than a traditional wing/tail airplane.
Designed properly, the canard should always stall before the main wing, thereby generating a recovering nose-down pitch. Unlike traditional wing/tail airplanes, however, there may not be noticeable buffet prior to the stall. A canard that stalls during the landing flare will likely result in airplane damage or worse.
(2) Canard designs typically have a rudder on each swept wing tip with each rudder only deflecting outward. This can feel natural to the pilot and actually helps minimize adverse yaw.
Unlike traditional airplanes, both rudders can be deflected simultaneously. While this can be a useful speed brake, it can also produce an unexpected pitching moment, due to the fact that the deflected rudder changes the air flow over the outboard wing section, which is aft of the
6/29/15 Appendix 6 airplane’s center of gravity (CG). Likewise, aileron effectiveness could be affected if it is within the influenced air flow.
(3) The dramatic wing sweep of canard design exists to locate the rudders far enough aft to be effective. An inevitable consequence of the sweep is a strong rolling tendency during uncoordinated flight. A sideslip can be generated by rudder deflection or a wind gust. In both cases, the airplane will likely weathervane back into the relative wind, but it will also roll away from the sideslip. In some canard designs, particularly during slow flight, this rolling tendency can be more powerful than can be countered with the ailerons.
(4) These designs often incorporate wheel brakes operated by applying force to the rudder pedal after fully deflecting the rudder. This design saves weight and space that normally accompanies a traditional toe brake system, but it means there is no braking without full rudder.
The system usually works well for taxi steering, but it warrants consideration and familiarity for crosswind takeoffs and landings.
d. Configurations. Other risks exist in the variety of control configurations.
(1) Some airplanes employ hand levers to operate the wheel brakes. Properly designed, these systems can perform adequately, although arm strength can become a factor in braking effectiveness. Unlike traditional foot-operated brakes, using hand brakes requires the pilot to release either the stick or the throttle (unless the lever is mounted on the stick). Applying differential braking with one hand operating two levers can be challenging. A setup where a single lever operates both wheel brakes works well only if it is perfectly rigged. Cable stretch, uneven brake wear, or uneven linkage wear can cause the application of more braking to one wheel without any way for the pilot to deal with it besides rerigging.
(2) Thrust lines vary among experimental airplanes. High-wing-mounted pusher configurations are common. Unlike traditional airplanes where increasing power usually causes a nose-up pitch, some of these designs produce the opposite airplane response. Although pilots can get used to applying an opposite direction stick displacement with every throttle change, it complicates maneuvers such as an aborted landing go-around. Thorough familiarity with your airplane’s power-pitch characteristics is essential for safe flight.
(3) How the pilot interfaces with the control surfaces has a large influence on workload, handling qualities, and overall satisfaction with the airplane. A short side-stick that requires a lot of effort to move limits maneuverability and will likely be worse at faster speeds. Finding the centered or neutral stick position as a primary step in an out-of-control situation can be very difficult with a side-stick. There’s no flying with your knees while you fold a chart or copy a clearance with a side-stick.
(4) Some pilots enjoy a tactile reference for their stick arm, usually by resting a forearm on their thigh. Side-stick designs without an arm rest deprive the pilot of this reference, which can make fine adjustments difficult and generate unwanted control inputs in turbulence. There are side-stick applications that have the stick between side-by-side seats. Poor design implementations can limit roll control due to interference with either occupant’s leg or hip.
6/29/15 Appendix 6 Page 3 (and 4)
3. RECOMMENDED GROUND TRAINING. Pilots should become thoroughly familiar with the location and force, displacement and operative sense requirements of their cockpit controls.
Practice blindfold cockpit exercises and simulated emergency procedures on the ground. Know your airplane’s systems, limits and recommended procedures before you begin flying. Consult the designer/kit vendor for advice. Discuss your situation with type club members and owner/builders of your airplane model. Internet forums and chat rooms may provide valuable information, but remember that the participants may or may not have the technical expertise you seek, and their airplanes may not exhibit identical handling qualities to your airplane.
4. RECOMMENDED FLIGHT TRAINING. A thorough airplane check-out by a qualified instructor preferably with recent experience in your airplane model is always a good idea. If you built the airplane yourself, consider obtaining this training from the kit vendor, preferably in your airplane, but the company demonstrator may provide sufficiently similar characteristics. If you purchased your airplane from a previous owner, learn all you can from him or her. Your training should emphasize the unique aerodynamic behavior of your airplane’s nontraditional configuration and any pilot compensation required to safely fly your airplane. If your airplane’s cockpit controls are different from what you are accustomed to, become familiar with the advantages and disadvantages of the design and explore your airplane’s handling qualities under safe, supervised conditions.
6/29/15 Appendix 7 APPENDIX 7. NONTRADITIONAL OR UNFAMILIAR AIRPLANE SYSTEMS
OPERATIONS
1. DEFINITION. Engine, avionics, fuel systems, etc., that require operational practices that are outside the normal procedures utilized in standard category airplanes.
2. DISCUSSION.
a. Example Accident from the National Transportation Safety Board (NTSB) Records.
(1) The pilot had recently purchased the experimental, amateur-built airplane, which had a fuel system that differed from the designer’s plans. The original builder had modified the fuel system by relocating the fuel selector handle from a position between the front pilot’s legs to a position behind and above his or her left shoulder. There were no markings for the operating positions of the fuel selector handle, which were up for off, down for the right tank, and to the right for the left tank.
(2) The pilot received a one-half hour flight and ground check-out in the airplane by another pilot familiar with the airplane model. The check-out pilot reported that the pilot needed a seatback cushion to be in position to reach the rudder pedals, and that he had difficulty reaching the fuel selector handle while seated with the cushion added. During preflight, the pilot was not observed to visually check the fuel. A maintenance technician noted that when the pilot was seated in the airplane, he had difficulty reaching the fuel selector handle. Also, he gave the pilot a mirror to look over his shoulder to see the unmarked, nonlinear fuel sight gauges, which were located in the rear cockpit. The pilot declined an offer for additional fuel, saying he would be airborne for only about 1 hour and did not need fuel.
(3) Ground witnesses saw the airplane in straight and level flight about 350 to 500 feet over a residential area, then they heard a reduction of engine noise. The airplane was seen to pitch slightly nose-up; then it banked sharply to the right and descended nose-first into the ocean.
The fuel selector valve was found in an intermediate position, about one-third open between the engine’s feed line and the right tank, and about 2-4 percent open to the left tank.
(4) Conditions were simulated using another airplane of the same design to evaluate the maneuver required to switch tanks from the front seat. The simulation revealed that four actions were required to change the fuel selector in flight:
• Remove pilot’s hand from the control stick;
• Loosen shoulder harness;
• Rotate upper body to the extreme left to reach the fuel selector handle; and
• Rotate the handle to an unmarked (not logically oriented) position.
(5) During the evaluation, investigators noted a natural reaction for the pilot’s right foot to depress the right rudder pedal when turning in the seat to reach the fuel selector handle. With the right rudder depressed in flight, the airplane would pitch up slightly and bank to the right.
6/29/15 Appendix 7
b. Probable Cause. The NTSB determines the probable cause(s) of this accident as follows:
(1) The pilot’s diversion of attention from the operation of the airplane and his inadvertent application of right rudder that resulted in the loss of airplane control while attempting to manipulate the fuel selector handle.
(2) Also, the Board determined that the pilot’s inadequate preflight planning and preparation, specifically his failure to refuel the airplane, was causal.
(3) The Board determined that the builder’s decision to locate the unmarked fuel selector handle in a hard-to-access position, unmarked fuel quantity sight gauges, inadequate transition training by the pilot, and his total lack of experience in this type of airplane were factors in the accident.
c. Type-Certificated (TC) versus Experimental Airplanes.
(1) TC’d airplanes familiar to most pilots have standardized instrument panel layouts and system control locations; they are very similar from airplane to airplane. Most airplanes found in the training and rental fleet are of similar performance and equipment levels. Pilots have become accustomed to operating flaps, fuel systems, retractable landing gear, and engine controls in these TC’d airplanes, and can generally transition from one make/model to another without the need for extensive training.
(2) Builders of experimental airplanes are able to customize every aspect of their airplane to their own personal preferences. This extends to the installation of systems not found on standard airplanes in the training and rental fleet, such as the fuel valve location discussed in the example above. Builders also sometimes place familiar instruments and controls in unfamiliar locations on the panel or in the cockpit area. This is true even in seemingly identical examples of a particular design. The ability to completely customize the airplane is one reason builders choose to build their own, rather than purchase a standard airplane. The hazard in operating these airplanes is the potential for misuse or system mismanagement. The risks of this misuse or mismanagement can include an inadvertently induced abnormal or emergency situation.
(3) Unlike TC’d airplanes, many experimental airplanes do not have extensive pilot’s operating handbooks (POH) or other documentation outlining the unique nature of the systems or controls installed in that particular airplane. This places the burden on the pilot to become familiar with the specific systems and controls in the airplane. Take care to identify every control and system on board the airplane.
3. RECOMMENDED GROUND TRAINING. The pilot should spend sufficient time sitting in the airplane on the ground learning the positions of all controls so as to be able to locate each control without the need to spend time searching. The pilot should utilize familiarization drills such as the “blindfold test”, where an assistant calls out various controls and switches while the pilot locates them by memory. The pilot should not fly the airplane before gaining thorough familiarity with cockpit layout. The pilot should also seek advice from previous operators of the airplane, including the original builder. The kit or plan vendor may also have useful information and advice.
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4. RECOMMENDED FLIGHT TRAINING. Flying the airplane with a previous operator, a knowledgeable flight instructor, or the original builder, prior to operating the airplane solo will help the pilot understand the reasons why the installed controls are the way they are and what operational characteristics they have. This will also guard against any unusual handling characteristics that may arise from application of a control or system that may catch the pilot off-guard, as illustrated in the example above.
6/29/15 Appendix 8 APPENDIX 8. NONTRADITIONAL OR UNFAMILIAR AIRPLANE SYSTEM OR
COMPONENT MAINTENANCE REQUIREMENTS
1. DEFINITION. Engine, avionics, propellers, fuel systems, etc., that require maintenance practices that are outside the normal procedures utilized in standard category airplanes.
2. DISCUSSION.
a. Example Accident from the National Transportation Safety Board (NTSB) Records.
(1) Accident. The airplane made a forced landing after the horizontal stabilizer attachment failed in flight. The instructional flight departed with the intention of practicing takeoffs and landings. On the downwind leg, the pilots heard a loud bang. The airplane lurched nose-up, then nose-down. The flight instructor took control of the aircraft and informed the tower he had a flight control problem. He was able to land the aircraft using cross control inputs. The instructor inspected the airplane and determined that the right horizontal stabilizer had separated from the fuselage due to a stainless steel “L” bracket failure. The instructor attributed the failure to a loose bolt in the “L” bracket that allowed a vibration and caused metal fatigue of the component.
(2) The Probable Cause. This accident was caused by the fatigue failure of the attachment that secured the horizontal stabilizer to the fuselage (due to improper maintenance— Federal Aviation Administration (FAA) comment).
b. Systems and Hardware.
(1) Manufacturers of type-certificated (TC) airplanes, as well as manufacturers of components and systems installed in such airplanes, provide supporting maintenance and repair documentation that shows owners and maintenance personnel how to properly maintain and repair the airplane. These documents are available from several sources and readily accessed by anyone performing maintenance or repair on these airplanes.
(2) Extensive maintenance documentation typically is not available for amateur-built and other experimental aircraft. Components and systems installed in these airplanes are sometimes the same or very similar to those installed in TC’d airplanes, so maintenance guidance may be available. However, many experimental airplanes incorporate components and systems not found on standard airplanes. Much like the experimental airframe itself, maintenance and repair guidance may be difficult to find or even unavailable for these components or systems.
(3) In the accident described above, the airplane suffered a failure due to improperly secured hardware, which led to a fatigue failure. This illustrates why owners and operators of experimental airplanes must make an extra effort to find and follow appropriate maintenance and repair guidance for their airplanes.