NTSB Final Report: Beech F33 | Aero-News Network
Aero-News Network
RSS icon RSS feed
podcast icon MP3 podcast
Subscribe Aero-News e-mail Newsletter Subscribe

Airborne Unlimited -- Most Recent Daily Episodes

Episode Date

Airborne-Monday

Airborne-Tuesday

Airborne-Wednesday Airborne-Thursday

Airborne-Friday

Airborne On YouTube

Airborne-Unlimited-05.05.25

Airborne-NextGen-05.06.25

AirborneUnlimited-05.07.25

Airborne-Unlimited-05.01.25

AirborneUnlimited-05.02.25

Thu, Mar 14, 2024

NTSB Final Report: Beech F33

Internal Failure Of The Autopilot Pitch Servo Actuator That Caused The Autopilot To Command A Nose Down Movement

Location: Bellefontaine, Ohio Occurrence Number: ENG22LA004
Date & Time: November 12, 2021, 09:02 Local Registration: N9035Q
Aircraft: Beech F33 Aircraft Damage: Minor
Defining Event: Sys/Comp malf/fail (non-power) Injuries: 1 None
Flight Conducted Under: Part 91: General aviation - Personal

Analysis: The pilot reported an uncommanded nose down pitch trim movement. The nose down pitch trim occurred immediately following the pilot’s engagement of the autopilot. The uncommanded nose down trim was repeated when the pilot engaged the autopilot later in the occurrence flight as well as during postflight troubleshooting. 

During the NTSB’s autopilot examination on the airplane, the uncommanded nose down pitch trim movement occurred repeatedly upon autopilot engagement. When the Garmin GSA 28 pitch servo actuator was removed and replaced with another GSA 28 servo, the uncommanded nose down pitch trim movement ceased.

The pitch servo actuator examination at Garmin resulted in test element failures (related to monitoring of the pitch servo torque) that, with the servo installed as part of the airplane’s autopilot, would have caused the autopilot pitch down movement, and, after several seconds, an automatic disconnect. Garmin’s analysis showed that an internal failure on the pitch servo actuator circuit card could cause uncommanded autopilot pitch trim movement before the autopilot would automatically disconnect.

As a result of the investigation, the FAA issued a notice of proposed rulemaking (NPRM) for various airplanes modified with the Garmin 500 GFC Autopilot System. The proposed Airworthiness Directive (AD) would require a mandatory software upgrade to the system. 

Probable Cause and Findings: The National Transportation Safety Board determines the probable cause(s) of this occurrence to
be -- The internal failure of the autopilot pitch servo actuator that caused the autopilot to command a nose down movement of the pitch trim.

FMI: www.ntsb.gov

Advertisement

More News

ANN's Daily Aero-Term (05.05.25): Circle To Runway (Runway Number)

Circle To Runway (Runway Number) Used by ATC to inform the pilot that he/she must circle to land because the runway in use is other than the runway aligned with the instrument appr>[...]

ANN's Daily Aero-Linx (05.05.25)

Aero Linx: National Aviation Safety Foundation (NASF) The National Aviation Safety Foundation is a support group whose objective is to enhance aviation safety through educational p>[...]

NTSB Prelim: De Havilland DHC-1

At Altitude Of About 250-300 Ft Agl, The Airplane Experienced A Total Loss Of Engine Power On November 6, 2024, at 1600 central standard time, a De Havilland DHC-1, N420TD, was inv>[...]

Classic Aero-TV: The Boeing Dreamliner -- Historic First Flight Coverage

From 2009 (YouTube Edition): Three Hour Flight Was 'Flawless' -- At Least, Until Mother Nature Intervened For anyone who loves the aviation business, this was a VERY good day. Afte>[...]

Airborne-NextGen 05.06.25: AF Uncrewed Fighters, Drones v Planes, Joby Crew Test

Also: AMA Names Tyler Dobbs, More Falcon 9 Ops, Firefly Launch Unsuccessful, Autonomous F-16s The Air Force has begun ground testing a future uncrewed jet design in a milestone tow>[...]

blog comments powered by Disqus



Advertisement

Advertisement

Podcasts

Advertisement

© 2007 - 2025 Web Development & Design by Pauli Systems, LC