Accident Piper PA-23-160 Apache (Seguin Geronimo conv.) N776MC,
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ASN Wikibase Occurrence # 265492
 
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Date:Thursday 15 July 2021
Time:11:29
Type:Silhouette image of generic PA23 model; specific model in this crash may look slightly different    
Piper PA-23-160 Apache (Seguin Geronimo conv.)
Owner/operator:Tri Flying Tigers Inc
Registration: N776MC
MSN: 23-1078
Year of manufacture:1957
Total airframe hrs:6885 hours
Engine model:Lycoming IO-360-C1C
Fatalities:Fatalities: 0 / Occupants: 2
Aircraft damage: Substantial
Category:Accident
Location:near Easton/Newnam Field Airport (ESN/KESN), Easton, MD -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Private
Departure airport:Annapolis-Lee Airport, MD (ANP/KANP)
Destination airport:Easton Airport, MD (ESN/KESN)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
On July 15, 2021, about 1129 eastern daylight time, a Piper PA-23, N776MC, was substantially damaged when it was involved in an accident near Easton, Maryland. The flight instructor and pilot receiving instruction were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight.

During an instructional flight, while performing a practice approach-to-landing stall with the flaps and landing gear extended, the pilot receiving instruction applied full power to both engines at the airframe buffet. While recovering, the left engine lost total power and the left propeller feathered uncommanded. At that time, the airspeed was about 57 mph and the airplane immediately rolled about 45° to the left, consistent with a Vmc roll. The flight instructor immediately took control of the airplane to recover. As he applied full right rudder, his seat slipped back, which released pressure on the right rudder pedal. The airplane entered a second Vmc roll, from which he was able to recover, but the airplane was at an altitude of about 1,100 ft agl and in a descent of about 800 ft per minute (fpm). The pilot receiving instruction was unable to restart the left engine, and the flaps and landing gear remained extended. When the airplane was flying below 700 ft agl and descending rapidly, both pilots realized that the airplane would not be able to reach the airport. The flight instructor subsequently landed the airplane with its landing gear and flaps still extended in a cornfield, during which the left wing and fuselage were substantially damaged. The airplane came to rest upright with both propellers feathered.

During a postaccident test run, the left engine produced full-rated power and manifold pressure with no hesitation noted during rapid full-throttle applications. No discrepancies were noted with either engine when a propeller oil control leak test procedure was performed on each. While the installed left propeller blades had a basic diameter that was 2 inches longer than the approved propeller, the propeller was not counterweighted as specified by the applicable supplemental type certificate, and the air charge in the propeller cylinder was about 2 psi less than the lower specified limit in the Propeller Owner’s Manual and Logbook, it is unlikely that those conditions would have resulted in to the uncommanded feathering of the left propeller. The propeller governor oil pump flow rate was measured to be slightly less than the minimum specified, the reason for the lower flow rate could not be determined because the test bench was not capable of measuring the internal leakage. The investigation also could not determine if the lower flow rate was sufficient to maintain the accident propeller at a low pitch while in a low power and airspeed flight condition. Based on this information, the reason for the total loss of engine power of the left engine and the reported uncommanded feathering of the left propeller could not be determined.

During the postaccident examination of the right front seat, a deformation in the tube-seat catch release was noted. That condition, which likely existed at takeoff, prevented one of the two seat catch plungers from extending into the seat track and likely allowed the seat to move back when the flight instructor applied right rudder. Given the described sequence of events provided by the flight instructor, the seat slipping directly contributed to the second Vmc roll and loss of altitude before he was able to recover. With an inoperative left engine, extension or retraction of the flaps and landing gear would have to be accomplished manually using a hand pump in the cockpit. If the seat slippage (and the subsequent loss of control and altitude) had not occurred, it is possible that either pilot would have had the time to manually retract the landing gear and flaps, and that the flight instructor could have flown with a single engine to a diversion airport.

Probable Cause: A total loss of left engine power and uncommanded feathering of the left propeller for reasons that could not be determined.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: ERA21LA289
Status: Investigation completed
Duration: 2 years 1 month
Download report: Final report

Sources:

https://www.wbaltv.com/article/small-plane-crash-easton-talbot-county/37038969
https://www.delmarvanow.com/story/news/local/maryland/2021/07/16/plane-crashes-near-easton-airport-investigation-underway-baileys-neck-road/7988797002/

NTSB
https://data.ntsb.gov/Docket?ProjectID=103488
https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=776MC
https://flightaware.com/live/flight/N776MC

https://myflightbook.com/logbook/public/ViewPic.aspx?r=Aircraft&k=257773&t=t_2021070314523342-2942032_.jpg (photo)

History of this aircraft

Other occurrences involving this aircraft
22 September 2020 N776MC Tri Flying Tigers Inc 0 Easton/Newnam Field Airport (ESN/KESN), Easton, MD unk
Gear-up landing

Location

Images:


Revision history:

Date/timeContributorUpdates
15-Jul-2021 23:19 Captain Adam Added
15-Jul-2021 23:48 RobertMB Updated [Source, Narrative]
16-Jul-2021 11:27 harro Updated [Location, Source, Narrative]
16-Jul-2021 16:20 Geno Updated [Source]
28-Aug-2023 10:42 Captain Adam Updated [[Source]]

Corrections or additions? ... Edit this accident description

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