Recommendation

The FAA has reviewed its current regulations and policies, and
decided to not adopt the specific recommendation. A copy of the
analysis accomplished by the FAA Small Airplane Directorate is
enclosed for your information.

14 CFR, part 23, §23.1155 states:

For turbine engine installations, each control for reverse
thrust and for propeller pitch settings below the flight regime
must have means to prevent its inadvertent operation. The means
must have a positive lock or stop at the flight idle position and
must require a separate and distinct operation by the crew to
displace the control from the flight regime (forward thrust regime
for turbojet powered airplanes).

The National Transportation Safety Board (NTSB) issued a safety
recommendation, A-94-62, dated March 2,1994, to revise 14 CFR, part
23, 23.1155 to require beta lock-out systems on small airplanes to
prevent operation of the propeller beta mode while in flight. The
National Transportation Safety Board cited similar instances on
different aircraft over the last 12 years supporting the safety
recommendation requiring an in-flight beta lock-out system. The FAA
stated its response to the NTSB in a letter dated March 20,
2001:

" ... based on the results of its evaluation, requiring beta
lock-out systems for small airplanes would most likely result in an
overall decrease in the level of safety for the small airplane
fleet. The FAA evaluated accident/incident data over a 20-year span
and found only one case where incorporation of a lock-out system
would have precluded the incident. However, the FAA found six
accidents/incidents caused by the inability to obtain beta when
needed. Incorporation of beta lock-out systems would most likely
cause this number to increase, effectively lowering the overall
level of safety for small airplanes. The service history shows that
a more critical consideration for small airplanes is the ability to
obtain beta on the ground when required."

The FAA reiterated its March 20, 2001 response to the NTSB in a
letter dated October 22, 2001:

"On March 20. 2001, the Federal Aviation Administration (FAA)
informed the Board that. based on the results of its evaluation,
requiring beta lock-out systems for small airplanes would most
likely result in an overall decrease level of safety for the small
airplane fleet."

The addition of a beta lock-out system requires increased system
complexity:

• Ground mode sensors: weight on wheels (WOW) switches, wheel
  spin-up sensors, radar altimeter, etc.
• Throttle quadrant beta lock-out solenoids.
• Throttle quadrant balk solenoids.
• Electronic control containing logic necessary for the
  interpretation of the ground mode sensors and the subsequent
  control of the throttle quadrant lock-out and balk solenoids.

Some of the associated failure modes of a beta lock-out system
include:

• Inability to achieve beta during ground operation due to
  failure of the ground mode sensors, throttle quadrant beta lock-out
  solenoids or electronic control.
• Inability to abort a landing once beta has been selected due to
  a failure of the balk solenoids or electronic control.
• Ability to select beta mode only on one engine due to a failure
  of one throttle quadrant beta lock-out solenoid, resulting in a
  large asymmetric thrust.

The Australian Transportation Safety Board (ATSB) Aviation
Occurrence Report - 200404589 Final, cites the in-flight usage of
beta in a Fairchild Industries SA227-AC Metro III aircraft as an
example supporting the safety recommendation. The FAA issued an
Airworthiness Directive (AD 92-18-07) on October 2, 1992
specifically addressing the flight idle detent functionality for
the Fairchild Aircraft (formerly Swearingen Aircraft Corporation)
SA226-T, SA226- T(B), SA226-AT, SA226-TC, SA227-TT, SA227-AT,
SA227-AC and SA227-BC Airplanes.

The specifics of the occurrence cited in the ATSB report clearly
point to a situation in which the Airplane Flight Manual (AFM)
procedures were not followed. There was a separate and distinct
operation by the crew to place the power lever in the beta range,
when the AFM specifically states that propeller reversing in flight
is prohibited.

Based upon the crew actions cited in the ATSB report, and our
position that requiring beta lockout systems for small airplanes
would most likely result in an overall decrease in the level of
safety for the small airplane fleet, we do not feel that any
further action is warranted. Therefore, we propose this
recommendation be classified this as "Closed - Not Adopted."