Accident Cessna 172M Skyhawk N9646Q,
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ASN Wikibase Occurrence # 289838
 
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Date:Saturday 21 December 2019
Time:13:06
Type:Silhouette image of generic C172 model; specific model in this crash may look slightly different    
Cessna 172M Skyhawk
Owner/operator:Hawk Aviation Inc
Registration: N9646Q
MSN: 17265730
Year of manufacture:1975
Total airframe hrs:8330 hours
Engine model:Lycoming O-320-E2D
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:near Rush City Regional Airport (ROS/KROS), Rush City, MN -   United States of America
Phase: Initial climb
Nature:Training
Departure airport:Rush City Regional Airport, MN (KROS)
Destination airport:Rush City Regional Airport, MN (KROS)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
On December 21, 2019, about 1306 central standard time, a Cessna 172M airplane, N9646Q, collided with trees following a loss of engine power shortly after takeoff from Rush City Regional Airport (ROS), Rush City, Minneapolis. The student pilot was not injured, and the airplane sustained substantial damage. The airplane was operated by Hawk Aviation Inc, Rush City, Minnesota, as a Title 14 Code of Federal Regulations Part 91 instructional flight. Day visual meteorological conditions prevailed, and no flight plan was filed for the local flight that was originating at the time of the accident.

The student pilot and his flight instructor completed an uneventful 15- to 20-minute flight in the airport traffic pattern before the flight instructor deboarded so the student pilot could continue on his first solo flight. The engine was not shut down while the flight instructor deboarded the airplane. The student pilot then taxied to the hold-short line for the runway where he completed an abbreviated before takeoff check, which included verifying that elevator trim was positioned for takeoff, carburetor heat was turned off, flaps were fully retracted, and that the fuel mixture control was full rich. The student pilot did not complete an engine runup before takeoff.

The student pilot stated that after takeoff, the airplane climbed to about 200 ft above the runway where the engine began to splutter briefly before a total loss of power. The airplane sustained substantial damage to the fuselage and both wings during a forced landing in a wooded area.

The flight instructor stated that he taught his students to pull the mixture control knob aft about 1 1/2 inches during taxi to avoid fouling the sparkplugs. The flight instructor recalled that he told the student pilot to lean the fuel mixture while they taxied back to the ramp at the completion of their dual-instruction flight. The flight instructor stated that shortly after the accident, the student pilot told him that the mixture control was pulled aft about 1 1/2 inches and that the carburetor heat control was on.

The student pilot subsequently reported that that he did not lean the fuel mixture during taxi and that leaning typically was only completed during cruise flight. Additionally, before he exited the airplane, the student pilot turned off the electrical master switch and both magnetos, repositioned the fuel selector from both to off, and pulled the mixture control knob full aft.

Postaccident examination revealed uncontaminated 100 low-lead aviation fuel present in the fuel strainer and the carburetor bowl. There was no evidence of fouling or excessive carbon deposits on the sparkplugs that would have prevented normal engine operation. The lack of fouling or excessive carbon deposits on the sparkplugs was consistent with a proper air-fuel mixture and normal carburetor function during the flight. Additionally, a postaccident engine test run did not reveal any mechanical anomalies with the engine that would have prevented normal operation during the flight.

Although the carburetor heat control system did not function properly during the test run, the sparkplugs did not exhibit features consistent with a carburetor icing situation that would have resulted in an excessively rich air-fuel mixture had the airflow through the carburetor venturi become restricted due to carburetor icing during the flight. Additionally, the engine test run confirmed that while at maximum static speed, the engine would stop running due to fuel starvation with the mixture control knob moved aft about 1 1/2 inches. It is likely that the student pilot did not reposition the mixture control to full rich before takeoff, which resulted in a total loss of engine power due to fuel starvation.

Probable Cause: The total loss of engine power due to fuel starvation because the student pilot failed to reposition the fuel mixture control to full rich before takeoff.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: CEN20LA042
Status: Investigation completed
Duration: 2 years and 9 months
Download report: Final report

Sources:

NTSB

Location

Images:


Photo: NTSB

Revision history:

Date/timeContributorUpdates
05-Oct-2022 18:48 Captain Adam Added

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