Date: 202008
Flight conditions: IMC
Aircraft: Airliner 99
Operator: Air Taxi
Operating under: Part 135
Mission: Cargo / Freight / Delivery
Flight phase: Cruise
Reporter organization: Air Taxi
Reporter function: Captain; Pilot Flying
Human factors: Confusion; Distraction; Training / Qualification
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Returned To Clearance; Flight Crew Became Reoriented
Contributing factors: Aircraft; Human Factors; Manuals; Procedure
Primary problem: Human Factors

Narrative: While reaching down for the rudder trim knob during cruise; I inadvertently deployed the flaps to 20%. The aircraft ballooned 200-300 ft. quickly as I corrected and notified ATC of the situation. The flaps never reached an over speed condition. I looked to my checklists for a solution to the problem. I then checked the circuit breaker panel. I advised ATC that I would need a block altitude to slow down within flap operating range; extend the flaps to 100%; and then retract them. This has worked on the ground in the past when flaps fail to retract after landing; always written up in the AML (Aircraft Maintenance Logbook). The flaps failed to retract upon the initial attempt so I proceeded to try cycling the flap handle again. When [I] retracted the flaps from the fully extended position on the second effort; I was unable to remain within the requested block of altitude. With the resultant loss of lift while also visually determining if the flaps had retracted on both the flap position indicator and outside the aircraft; I exercised PIC (Pilot in Command) authority to quickly [request priority handling]. Once the aircraft was stabilized and I was able to confidently determine which configuration the aircraft flaps were in; I notified ATC that I [no longer needed priority handling] and would then proceed on course. [I was] instantly aware of the change in flap position via [the] 200-300 ft. gain in altitude and forward pressure required to combat this. Human error caused the inadvertent deployment of flaps. Flight control malfunction caused the inability to retract the flaps. [I] notified ATC immediately when [the] flaps were inadvertently deployed and also when I was unable to retract the flaps - flight control malfunction. I ran my abnormal and emergency checklists; but neither addressed the current situation. I wasted no time in [requesting priority handling] when I was unable to maintain the block altitude given. My first priority was to fly the plane; but also make the world bigger and get more people involved. Once I was confident in the safe operation of the aircraft and its ability to complete our mission; I again advised ATC of my intentions. Being more conscious with hand movements in the flight deck will prevent this event from occurring again. If I would have first confirmed with my eyes before reaching for the rudder trim knob; I believe I would not have inadvertently bumped the flap handle and deployed the flaps to 20%. I also believe that a QRH for the [aircraft] would have assisted me in determining whether the smartest course of action would be to leave the flaps in the 20% extended configuration or cycle the flap handle. The greatest risk in cycling the flaps to 100% and then 0% is that there is no guarantee they will retract once fully extended. Hindsight being 20:20 I believe leaving the flaps in the 20% configuration for the remainder of the flight would have been the better choice. I have learned from the situation and will teach others from this experience.




Synopsis: BE99 Captain reported inadvertently deploying flaps in cruise.