Accident Lancair IV-P N37MB, Friday 17 November 2023
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Date:Friday 17 November 2023
Time:17:08
Type:Silhouette image of generic LNC4 model; specific model in this crash may look slightly different    
Lancair IV-P
Owner/operator:Maxess Inc
Registration: N37MB
MSN: LIV-362
Fatalities:Fatalities: 0 / Occupants: 1
Other fatalities:0
Aircraft damage: Substantial
Category:Accident
Location:Perry, FL -   United States of America
Phase: En route
Nature:Private
Departure airport:Bryan-Coulter Field, TX (CFD/KCFD)
Destination airport:Tampa North Aero Park, FL (X39)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
On November 17, 2023, about 1708 eastern standard time, an experimental amateur-built Lancair IV-P, N37MB, was substantially damaged when it was involved in an accident near Perry, Florida. The pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The pilot reported a loss of engine power after descending from 11,500 ft mean sea level (msl) and leveling off under a cloud layer at 2,000 ft msl. The pilot switched fuel tanks and enrichened the mixture; however, he was unable to restore engine power and elected to execute a forced landing during which he impacted trees.

Postaccident examination of the airframe and fuel-injected engine revealed no anomalies that would have precluded normal operation. The engine subsequently started without hesitation during a test cell run at the manufacturer’s facility. After running at idle for 5 minutes, the engine was run for 5 minutes at various rpm settings. The engine test run revealed that the fuel system was mal-adjusted and set too lean, and the manifold pressure was about 2 inches of mercury lower than that required to produce rated power. This could have been due to an observed leak of the turbocharger exhaust or the sonic venturis which were open to the atmosphere for the engine test.

Following these static engine runs, the engine was brought to idle and then the throttle was rapidly advanced. When the throttle was advanced quickly, the engine ran very rich with black exhaust smoke, and then would falter. If the throttle was not immediately retarded, the engine lost power completely. If the engine was immediately brought back to idle after it faltered upon rapid throttle advancement, the engine regained power. This was consistent with the engine flooding with rapid throttle advancement after a period of idling.

Given that no anomalies were noted in the examination and that the engine repeatedly stopped producing power after rapid throttle advancement after a period of idling in the test cell, it is possible that the speed with which the pilot advanced the throttle after leveling from the descent was too quick. The engine likely then would have flooded with fuel and stopped producing power, similar to the behavior observed during the postaccident test run.

Probable Cause: A rapid throttle advancement after a period of idling, which resulted in a flooded engine and total loss of engine power.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: ERA24LA043
Status: Investigation completed
Duration: 8 months
Download report: Final report

Sources:

NTSB

https://data.ntsb.gov/Docket?ProjectID=193406
https://www.aircraft.com/aircraft/200989365/n37mb-1999-lancair-iv-p

Location

Images:


Photo: FAA

Revision history:

Date/timeContributorUpdates
21-Nov-2023 18:34 Captain Adam Added
01-Dec-2023 17:11 Captain Adam Updated [Time, Phase, Departure airport, Destination airport, Narrative, Category, Accident report, ]
09-Sep-2024 08:29 Captain Adam Updated [Source, Narrative, Photo, ]

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