Fri, Mar 26, 2010
Calls Accident Rate For Some Models "Large And
Disproportionate"
The FAA has issued an Information for Operators (InFO)
report for amateur-built experimental Lancair and other
amateur built airplanes possessing high wing loading and stall
speeds in excess of 61 knots. The FAA says analysis of fatal
accidents for airplanes operating under an experimental
airworthiness certificates, such as the Lancair, has revealed a
large and disproportionate number of fatal accidents for their
fleet size. Though the FAA has seen a recent downward trend, these
aircraft types have experienced fatal accident rates substantially
higher than for-personal-use general aviation and the overall fatal
accident rate for all amateur-built experimental aircraft. The FAA
believes that this is mainly due to the pilot’s lack of
awareness of the slow-flight and stall characteristics of these
type of high performance aircraft. Also, the nature of
amateur-built aircraft means that each amateur-built aircraft may
have unique flight handling characteristics.
Analysis conduced by the FAA over the past few years shows a
number of fatal accidents occurred in these types of aircraft. A
majority of the fatal accidents occurred due to inadvertent
stall/spins while at slower airspeeds in home airport traffic
patterns.
Amateur built experimental aircraft are not required to be type
certificated in accordance with Title 14 of the Code of Federal
Regulations (14 CFR) part 23 – Airworthiness Standards:
Normal, Utility, Acrobatic, and Commuter Category Airplanes.
Stability, handling, and stall characteristics for the
amateur-built experimental airplanes are different from general
aviation airplanes that are type certificated under part 23. In
addition to not meeting the part 23 certifications standards,
aircraft such as the Lancair are high-performance, hand-made
(nonproduction) aircraft. Each individual amateur built
experimental aircraft possessing high wing loading and stall speeds
in excess of 61 knots can have unique handling, stability, and
stall characteristics. These design characteristics, while allowing
for higher operational speeds, can expose pilots to additional risk
during slowspeed operations while close to the ground and with
little time to recover from an unintentional stall. Understanding
these differences is critical for safe operation of such
aircraft.
Lancair Evolution File Photo
The FAA recommends that pilots operating the amateur built
experimental aircraft, such as the Lancair amateur-built
experimental airplanes do the following:
- Review and thoroughly understand all available information
regarding the slow-flight and stall characteristics of their own
Lancair prior to attempting to duplicate these maneuvers. In
addition, obtain specialized training from a Lancair recommended
flight instructor who has had adequate training in the Lancair
model or other similar high-performance airplanes to experience
slow flight handling characteristics, stall recognition, and stall
recovery techniques.
- Install an angle-of-attack (AOA) indicator and/or a stall
warning indicator to provide warning of an impending stall. Owners
that already have an AOA and/or a stall warning indicator installed
should have the calibration validated to assure proper operation.
Amateur built experimental aircraft can possess flight
characteristics, including stall speeds, which can vary from
airplane to airplane. (Note: indicated airspeeds can be as much as
10-20% off if the pitot tube is not in the proper location, or if
not properly calibrated and verified).
- Amateur built experimental aircraft possessing high wing
loading and stall speeds in excess of 61 knots, such as the
Lancair, should have their aircraft evaluated by a mechanic with
sufficient builders and maintenance experience to verify proper
rigging, wing alignment, and weight and balance. Lancair airplane
builders should use the services of experienced and qualified
construction evaluators who are familiar with the Lancair and/or
other similar aircraft construction, rigging, flight, and handling
characteristics.
- Owners of amateur built experimental aircraft possessing high
wing loading and stall speeds might wish to have their aircraft
evaluated by a qualified test pilot to determine the aircraft's
handling characteristics prior to adding any suggested aerodynamic
improvement and where appropriate, have items such as leading
edge wing cuffs and/or strakes installed and then tested, by a
qualified test pilot to verify
- improvements to the aircraft’s handling characteristics
and or reduction in stall speed before permanent attachment.
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