Accident Piper PA-23 Apache N233P,
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ASN Wikibase Occurrence # 224432
 
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Date:Saturday 27 April 2019
Time:09:45 LT
Type:Silhouette image of generic PA23 model; specific model in this crash may look slightly different    
Piper PA-23 Apache
Owner/operator:Private
Registration: N233P
MSN: 23-604
Year of manufacture:1956
Total airframe hrs:3823 hours
Engine model:Lycoming O-320-B3B
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:near Sulphur Springs Municipal Airport, TX -   United States of America
Phase: Landing
Nature:Private
Departure airport:Mount Pleasant Regional Airport, TX (KOSA)
Destination airport:Mount Pleasant Regional Airport, TX (KOSA)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The pilot of a twin-engine airplane was in cruise flight when the left engine lost partial power. He turned on the boost pumps, checked the fuel quantity and engine gauges, verified fuel tank selection, and added throttle. However, the left engine continued to lose power. The pilot reported that, without warning, the right engine lost total power and would not restart. The right propeller went to the feathered position. The pilot initiated a forced landing to a field. During the descent, the left engine lost total power but the propeller continued to rotate, and the left engine was unresponsive to throttle input. During the forced landing, the airplane sustained substantial damage to the left and right wings and the fuselage.
Examination of the right engine found the magneto timing at 12.5º (data plate specifies 25º). Otherwise, no preimpact abnormalities were noted during the right engine examination that would have precluded normal operations. The investigation was not able to determine why the right propeller was stopped in the feathered position.
Examination of the left engine found the magneto timing at 23º. The bolts that secured the upper and lower halves of the carburetor were found loose. When the carburetor was opened, the inside of the bowl was dry, and the gasket appeared worn, consistent with rubbing between the two carburetor halves. The top set of spark plugs displayed heavy carbon coating consistent with the left engine running at a rich fuel setting. During a test run, the left engine would not produce rated power and ran rich. When the mixture was leaned, the left engine ran smooth and ran normally. The carburetor was bench tested and operated as expected. The carburetor was disassembled, and evidence of water staining was present.

A fuel sample collected from the left side fuel tank appeared divided with the top part blue, consistent with 100 LL avgas, and the lower portion of the liquid was clear with brown sediment visible at the intersection of the two liquids. The fuel strainer bowl revealed rust colored liquid and sediment in the bowl. The fuel strainer screen contained numerous small flakes of an unidentified contaminant. A sample of fuel drained from the left-wing tank tested positive for water when tested with water-finding paste. The loss of power on the left engine is likely due to water contamination.

Probable Cause: The pilot's inadequate preflight inspection, during which he failed to detect the water contamination in the left fuel, which resulted in a partial loss of power in the left engine. Contributing to the accident was the total loss of power in the right engine for undetermined reasons.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: CEN19LA129
Status: Investigation completed
Duration: 2 years and 5 months
Download report: Final report

Sources:

NTSB CEN19LA129

FAA register: https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=233P

Location

Revision history:

Date/timeContributorUpdates
28-Apr-2019 00:37 Geno Added
08-Jul-2022 18:12 ASN Update Bot Updated [Time, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative, Category, Accident report]
12-Sep-2023 21:04 Ron Averes Updated [[Time, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative, Category, Accident report]]

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