# NTSB CEN19LA129: Piper PA 23, N233P, Sulphur Spring, TX, April 27, 2019 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: April 27, 2019, 09:45 local (14:45 UTC) - Place: Sulphur Spring, TX - Coordinates: 33.193054, -95.611389 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.1931&lon=-95.6114&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Fuel contamination](https://openairdocs.org/ntsb-events/193) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: Piper Aircraft Company, FAA FSDO - NTSB case key (mKey): 99329 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN19LA129 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/99329/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=99329 - Page: https://openairdocs.org/ntsb/CEN19LA129 ## 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. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Fluids: fuel](https://openairdocs.org/ntsb-findings/01071010): Aircraft › Fluids/misc hardware · Fluid condition (probable cause); cases with it: [Piper PA-23, 3 cases](https://openairdocs.org/ntsb-findings/01071010/cases.md?model=7102302), [All aircraft, 1,695 cases](https://openairdocs.org/ntsb-findings/01071010/cases.md) - [Engine fuel and control: fuel control/carburetor](https://openairdocs.org/ntsb-findings/01057322): Aircraft › Aircraft power plant · Inadequate inspection (probable cause); cases with it: [Piper PA-23, 1 case](https://openairdocs.org/ntsb-findings/01057322/cases.md?model=7102302), [All aircraft, 195 cases](https://openairdocs.org/ntsb-findings/01057322/cases.md) - [Engine (reciprocating)](https://openairdocs.org/ntsb-findings/01058500): Aircraft › Aircraft power plant · Unknown/Not determined (probable cause); cases with it: [Piper PA-23, 3 cases](https://openairdocs.org/ntsb-findings/01058500/cases.md?model=7102302), [All aircraft, 497 cases](https://openairdocs.org/ntsb-findings/01058500/cases.md) - [Inspection: preflight inspection](https://openairdocs.org/ntsb-findings/02061510): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Piper PA-23, 3 cases](https://openairdocs.org/ntsb-findings/02061510/cases.md?model=7102302), [All aircraft, 551 cases](https://openairdocs.org/ntsb-findings/02061510/cases.md) - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [Piper PA-23, 4 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=7102302), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Prior to flight: Aircraft inspection event](https://openairdocs.org/ntsb-events/050); cases with it: [Piper PA-23, 3 cases](https://openairdocs.org/ntsb-events/050/sequence.md?model=7102302), [All aircraft, 229 cases](https://openairdocs.org/ntsb-events/050/sequence.md) - [Enroute-cruise: Fuel contamination](https://openairdocs.org/ntsb-events/193) (defining event); cases with it: [Piper PA-23, 1 case](https://openairdocs.org/ntsb-events/193/sequence.md?model=7102302), [All aircraft, 225 cases](https://openairdocs.org/ntsb-events/193/sequence.md) - [Enroute-cruise: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342); cases with it: [Piper PA-23, 2 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=7102302), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Enroute-descent: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341); cases with it: [Piper PA-23, 5 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=7102302), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Landing: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Piper PA-23, 4 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=7102302), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis 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. ## Factual narrative On April 27, 2019, about 0945 central daylight time, a Piper PA-23 airplane, N233P, was substantially damaged when it was involved in an accident near Sulphur Springs Municipal Airport (SLR), Sulphur Springs, Texas. The pilot was not injured. The flight was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that before departure from Mount Pleasant Regional Airport (OSA), the airplane’s main fuel tanks were “topped off.” The pilot added that as he passed over SLR, he noticed a slight drop in rpm on the left engine. He increased the left engine manifold pressure to "full," but the engine speed continued to decrease. He observed a small amount of black smoke coming from left engine and checked that the fuel primer was still locked. The airspeed was decreasing, so he decided to turn back to SLR. He turned on the boost pumps, then checked the fuel quantity, verified the fuel selector was set to the main tanks, and checked the engine gauges. The left engine tachometer showed only 2,000 rpm, with full throttle. The airplane was about 3,000 ft mean sea level (msl) and descended 100 to 200 ft per minute while the airspeed decreased. The pilot stated that, "with no warning, the right engine died." He attempted to restart it, but the right engine would not restart, and the propeller went to the feathered position. The airplane was not able to maintain altitude or airspeed, so the pilot located a field to perform a forced landing. As he descended to the field, the left engine lost power. The pilot stated that the “left engine continued to windmill but was not responsive to throttle changes.” After the forced landing and the airplane came to rest, the pilot turned off the fuel pumps, fuel, avionics, and the master switch. During the forced landing, the airplane sustained substantial damage to the left and right wings and the fuselage. After the airplane was recovered, an examination was conducted on the engines and airframe. About 45 gallons of fuel was recovered from the airplane’s main fuel tanks. The left-wing main fuel tank appeared intact, and fluid was observed in the fuel cell when viewed from the filler opening. A sample of fuel 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 contained rust colored liquid and sediment. The fuel strainer screen contained numerous small flakes of an unidentified material. A sample of fuel drained from the left tank tested positive for water when tested with Kolor-Kut water finding paste. A fuel sample taken from the right-wing tank appeared blue; consistent with 100 LL avgas. The fuel strainer bowl and screen were absent debris/contaminants. Examination of the right engine found the magneto timing at 12.5º (data plate specifies 25º). Otherwise no preimpact abnormalities werenoted during the engine examination. The right engine’s two-bladed propeller was found in the feathered position. Both blades appeared straight absent bending. Examination of the left engine found the magneto timing at 23º (data plate specifies 25º). 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 engine running at a rich fuel setting. A non-original equipment manufacturer air induction system was observed and appeared free of any blockages. The left engine’s two-bladed propeller was not in the feathered position. Both blades showed signs of polishing with slight S-bending of the blades. The left engine was mounted on a test stand, the bent propeller was replaced with the propeller from the right engine. An engine test run was completed and noted that the left engine would not produce rated power and ran rich. The fuel mixture control was leaned, and the left engine smoothed out and ran normally. The carburetor was bench tested and operated as expected. The carburetor was disassembled, and evidence of water staining was present. ## Aircraft - Registration: [N233P](https://openairdocs.org/deregistered/N233P-2020-09-04), registration cancelled 2020-09-04, S/N 23-604, built 1956 (OpenAirDocs) - Reported make and model: Piper PA 23 (Undesignat) - Registry model: [Piper PA-23](https://openairdocs.org/model/piper-pa-23) (registry code 7102302) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 23-604 - Year built: 1956 - Airframe hours: 3823.2 - Engines: Lycoming O-320-B3B 160 hp reciprocating; Lycoming O-320-B3B 160 hp reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 8, 2019 - Departed: OSA, Mount Pleasant, TX - Destination: OSA, Mount Pleasant, TX - Equipment: Auto-pilot, ADS-B, Electronic multifunction display ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 47; injuries: none; private; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 3, without waivers/limitations; last flight review June 4, 2018; seat: left; restraint: lap only; flight hours: 398 total, 35 in this make and model, 286 as pilot in command, 16 in the last 90 days, 11 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 220° at 13 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 59 °F - Altimeter: 29.94 inHg - Observed at: KSLR, 2 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20190427010939A](https://openairdocs.org/incident/20190427010939A), Apr 27, 2019: Piper PA-23, Sulphur Springs, TX, Substantial damage. Pilot stated he had experienced a dual engine failure and had to do a forced landing into a field. He indicated the left engine was dropping RPM and he was… ## Docket (10 files) The files NTSB released with the investigation on September 22, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=99329. 13.1 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 2.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12417625&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - FAA inspector's statement (item 2, PDF, 1 page, 83 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12421553&FileExtension=pdf&FileName=Inspectors%20Statement%20for%20aircraft%20N233P_Redacted-Rel.pdf - Fuel receipt (item 3, PDF, 1 page, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12421364&FileExtension=pdf&FileName=Fuel%20and%20Oil_Redacted-Rel.pdf - Maintenance records (item 4, PDF, 17 pages, 4.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12420836&FileExtension=pdf&FileName=CEN19LA129%20Airframe%20Maintenance%20Records-Propeller%20Maintenance%20Records-Engine%20Maintenance%20Records_Redacted-Rel.pdf - Photos (item 5, PDF, 9 pages, 2.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12421225&FileExtension=pdf&FileName=N233P%20Apache%20-%20Aircraft%20Damages%20Photo%20Sheet-Rel.pdf - Examination (item 6, PDF, 9 pages, 197 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12421117&FileExtension=pdf&FileName=CEN19LA129%20-%20Wreckage%20Exam%20Notes2-Rel.pdf - Engine run (item 7, PDF, 2 pages, 278 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12421608&FileExtension=pdf&FileName=Engine%20run_Redacted-Rel.pdf - Statement of party representatives to NTSB investigation (item 8, PDF, 1 page, 229 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12421254&FileExtension=pdf&FileName=Piper%20signed%20NTSB%20Party%20Form%20-%20CEN19LA129_Redacted-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 9, PDF, 1 page, 647 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12420846&FileExtension=pdf&FileName=Ken%20Colby%20NTSB%20wreckage%20release%20sign_Redacted-Rel.pdf - PA-23 AFM (item 10, PDF, 29 pages, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12425220&FileExtension=pdf&FileName=Report%200832%20PA-23%20AFM-Rel.pdf From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.