# NTSB CEN23LA418: Beech C23, N18994, Gonzales, TX, September 24, 2023 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: September 23, 2023, 19:14 local (Sep 24, 2023, 00:14 UTC) - Place: Gonzales, TX - Coordinates: 29.525311, -97.457816 - Nearby events: https://openairdocs.org/map.md?lat=29.5253&lon=-97.4578&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach-VFR go-around: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: Textron Aviation, Lycoming, Federal Aviation Administration - NTSB case key (mKey): 193123 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN23LA418 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/193123/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=193123 - Page: https://openairdocs.org/ntsb/CEN23LA418 ## Probable cause The loss of engine power during go-around due to a failed muffler flame tube, which resulted in an exhaust blockage. Contributing to the accident was maintenance personnel's inadequate inspection of the exhaust system during the most recent maintenance. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine exhaust](https://openairdocs.org/ntsb-findings/01057800): Aircraft › Aircraft power plant · Fatigue/wear/corrosion (probable cause); cases with it: [Beech C23, 1 case](https://openairdocs.org/ntsb-findings/01057800/cases.md?model=1151242), [All aircraft, 56 cases](https://openairdocs.org/ntsb-findings/01057800/cases.md) - [Engine exhaust](https://openairdocs.org/ntsb-findings/01057800): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Beech C23, 1 case](https://openairdocs.org/ntsb-findings/01057800/cases.md?model=1151242), [All aircraft, 56 cases](https://openairdocs.org/ntsb-findings/01057800/cases.md) - [Engine exhaust](https://openairdocs.org/ntsb-findings/01057800): Aircraft › Aircraft power plant · Inadequate inspection (probable cause); cases with it: [Beech C23, 1 case](https://openairdocs.org/ntsb-findings/01057800/cases.md?model=1151242), [All aircraft, 56 cases](https://openairdocs.org/ntsb-findings/01057800/cases.md) - [Inspection: scheduled/routine inspection](https://openairdocs.org/ntsb-findings/02061520): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Beech C23, 2 cases](https://openairdocs.org/ntsb-findings/02061520/cases.md?model=1151242), [All aircraft, 167 cases](https://openairdocs.org/ntsb-findings/02061520/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Approach-VFR go-around: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Beech C23, 10 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=1151242), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) ## Analysis According to the pilot, while on final approach to the runway he experienced wind shear and elected to go around. He applied full throttle and began to climb out when the engine sustained a loss of power, so he made a forced landing to a field off the left side of the runway. The airplane collided with a fence and a tree, which separated the right wing near the wing root. Postaccident examination of the exhaust system revealed that a portion of the muffler flame tube had failed and blocked at least 95% of the tailpipe exit path. The piece of flame tube was lodged in the tailpipe. A 3-inch crack was noted on the muffler endcap opposite of the separated flame tube. There were no other mechanical malfunctions or failures that would have precluded normal operation. The muffler had been repaired and reinstalled on the airplane about 23 years before the accident and accumulated 504.84 hours. The most recent 100-hour/annual inspection, which was completed 55.4 hours before the accident, failed to identify the degraded and corroded flame tube. ## Factual narrative On September 23, 2023, about 1914 central daylight time, a Beech C23 airplane, N18994, was substantially damaged when it was involved in an accident near Gonzales, Texas. The pilot received minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. According to the pilot, he intended to complete a personal flight to Roger M Dreyer Memorial Airport (T20), Gonzales, Texas. During the final approach to runway 15 he experienced wind shear and elected to go around. He applied full throttle and began to climb out when the engine sustained a loss of power, so he made a forced landing to a field off the left side of the runway. The airplane collided with a fence and a tree, which separated the right wing near the wing root. Postaccident examination of the airplane revealed substantial damage to the wings and fuselage. The undamaged exhaust system was examined using a flashlight in the tailpipe and a lighted borescope, which revealed a blockage in the tailpipe; the muffler was then removed and cut open. The flame tube was blocking at least 95% of the tailpipe exit path; the piece was lodged in the tailpipe. The fracture area appeared degraded and covered in corrosion. A 3-inch crack was noted on the muffler endcap opposite of the separated flame tube. There were no other mechanical malfunctions or failures that would have precluded normal operation. The airplane maintenance logbooks revealed that, during a maintenance inspection on December 24, 1997 (3,523.42 hours total time and 1,260.42 hours since major overhaul), the exhaust system was inspected “for leaks and cracks. System found to be satisfactory.” On January 2, 1999 (3,556.5 hours total time and 1,293.50 hours since major overhaul), another maintenance inspection was conducted by the same mechanic and there was no mention of the exhaust system. On March 21, 2000, the airplane’s muffler was repaired and inspected by a separate exhaust system repair station. The work order for this muffler repair revealed that the muffler was to be inspected and repaired. The items replaced included: 3 tabs, the outer shell, 2 caps, 2 flame tubes, 2 elbows, 2 beaded ends, 2 end plates, and the tailpipe. On April 1, 2000 (3,603.36 hours total time and 1,340.36 hours since major overhaul), another maintenance inspection was conducted by the same mechanic from 1997 and 1999, when they reinstalled the repaired muffler. There were no additional maintenance logbook entries found specifically related to a muffler repair or replacement. The most recent 100-hour/annual inspection was completed on November 23, 2022, (4,052.8 hours total time and 1,789.8 hours since major overhaul), during which 8 exhaust clamps were replaced and a new exhaust stud was installed on the No. 4 cylinder. There was no specific mention of the muffler; however, 14 CFR Part 43 Appendix D—Scope and Detail of Items (as Applicable to the Particular Aircraft) To Be Included in Annual and 100-HourInspections, states in part: (d) Each person performing an annual or 100-hour inspection shall inspect (where applicable) components of the engine and nacelle group as follows: (8) Exhaust stacks—for cracks, defects, and improper attachment. The installed Dynon Avionics revealed that the airplane total time was 4,108.2 hours at the time of the accident. Therefore, the muffler had been installed on the airplane for 504.84 hours. Beech maintenance and overhaul documents revealed that the exhaust system should be overhauled or replaced every 800 hours or when the condition warrants replacement. The exhaust muffler and shroud should be inspected every 100 hours. The documentation states, “It is recommended that at each 100 hour and/or annual inspection, all exhaust muffler shrouds be removed and the muffler thoroughly inspected for cracks, leaks and (if applicable) deterioration of the internal tubes which could cause a decrease in engine power due to blockage of the exhaust. According to the Federal Aviation Administration (FAA) FAA-H-8083-32B, Aviation Maintenance Technician Handbook – Powerplant: Internal Muffler Failures Internal failures (baffles, diffusers, etc.) can cause partial or complete engine power loss by restricting the flow of the exhaust gases. If pieces of the internal baffling breaks loose and partially or totally blocks the flow of exhaust gases, engine failure can occur. As opposed to other failures, erosion and carburization caused by the extreme thermal conditions are the primary causes of internal failures. Engine backfiring and combustion of unburned fuel within the exhaust system are probable contributing factors. In addition, local hot-spot areas caused by uneven exhaust gas flow can result in burning, bulging, or rupture of the outer muffler wall. Exhaust System Repairs It is generally recommended that exhaust stacks, mufflers, tailpipes, etc., be replaced with new or reconditioned components rather than repaired. Welded repairs to exhaust systems are complicated by the difficulty of accurately identifying the base metal so that the proper repair materials can be selected. Changes in composition and grain structure of the original base metal further complicate the repair. However, when welded repairs are necessary, the original contours should be retained; the exhaust system alignment must not be warped or otherwise affected. Repairs or sloppy weld beads that protrude internally are not acceptable as they cause local hot spots and may restrict exhaust gas flow. FAA Advisory Circular (AC) 91-59A, "Inspection and Care of General Aviation Aircraft Exhaust Systems," emphasizes "the safety hazards of poorly maintained aircraft exhaust systems (reciprocating powerplants) and highlights points at which exhaust system failures occur. Further, it provides information on the kinds of problems to be expected and recommends pilots perform ongoing preventive maintenance and mechanics perform maintenance." The AC also notes thatpotential failures can include partial or full engine power loss caused by loose baffles, cones, or diffusers on mufflers and heat exchangers that partially or completely block the exhaust gas outlet flow. ## Aircraft - Registration: [N18994](https://openairdocs.org/deregistered/N18994-2024-04-06), registration cancelled 2024-04-06, S/N M-1998, built 1977 (OpenAirDocs) - Reported make and model: BEECH C23 - Registry model: [Beech C23](https://openairdocs.org/model/beech-c23) (registry code 1151242) (OpenAirDocs) - Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: M-1998 - Year built: 1977 - Airframe hours: 4052.8 - Engines: Lycoming O-360-A4K 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, November 23, 2022, 55 hours before - Departed: KHYI, San Marcos, TX - Destination: Same as departure - Airport: T20, Roger M Dreyer Meml, runway 15, 3,200 × 50 ft, asphalt - Equipment: Electronic multifunction display, Electronic flight bag or handheld device, Data recorder, ADS-B, Handheld GPS, Electronic primary flight display ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 43; injuries: minor; private; airplane ratings: single-engine land; medical: class 3, without waivers/limitations; last flight review October 29, 2022; seat: left; restraint: 3-point; flight hours: 210.9 total, 162.7 in this make and model, 125 as pilot in command, 28 in the last 90 days, 14 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 10 knots, gusting 17 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 97 °F, dew point 70 °F - Altimeter: 29.81 inHg - Observed at: KBAZ, 33 nm away - METAR: KBAZ 232351Z AUTO 16013KT 10SM CLR 37/20 A2980 RMK AO2 SLP078 T03670200 10389 20356 55005 ## 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 20230923015899A](https://openairdocs.org/incident/20230923015899A), Sep 23, 2023: Beech C23, Gonzales, TX, Substantial damage. Aircraft experienced loss of power on go around. Lack of altitude limited the landing options. Aircraft made a left-hand turn and touched down in a field. Went… ## Docket (11 files) The files NTSB released with the investigation on May 9, 2024, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=193123. 207 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 13.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16627413&FileExtension=pdf&FileName=6120%20-%20pilot%20(signed)_Redacted-Rel.pdf - NTSB examination summary (item 2, PDF, 7 pages, 148 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16627080&FileExtension=pdf&FileName=NTSB%20Exam%20Summary-Rel.pdf - Photos (item 3, PDF, 13 pages, 12 photos, 6.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16627423&FileExtension=pdf&FileName=Photos-Rel.pdf - Maintenance records (item 4, PDF, 22 pages, 172 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16626425&FileExtension=pdf&FileName=Mx%20docs%20and%20manuals_Redacted-Rel.pdf - FAA advisory circular ac 91-59A inspection and care of general aviation aircraft exhaust systems (item 5, PDF, 7 pages, 62 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16633178&FileExtension=pdf&FileName=AC_91-59A-Rel.pdf - FAA-H-8083-32B, aviation maintenance technician handbook a�� powerplant - excerpt (item 6, PDF, 1 page, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16633869&FileExtension=pdf&FileName=Pages%20from%2005_amtp_ch3-Rel.pdf - Reports from parties to the investigation - Textron aviation (item 7, PDF, 10 pages, 865 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16949898&FileExtension=pdf&FileName=Textron%20Tech%20Report%20M-1998_Redacted-Rel.pdf - Dynon avionics data (item 8, CSV, 9.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16627674&FileExtension=csv&FileName=N18994-SN23510-BLACK_BOX_LOG_DATA-Rel.csv - FAA ADS-B data (item 9, XLSX, 3.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16627606&FileExtension=xlsx&FileName=20230923_A165CB_528384053_ADSB-Rel.xlsx - Release of aircraft wreckage, NTSB form 6120.15 (item 10, PDF, 1 page, 113 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16627564&FileExtension=pdf&FileName=Wreckage%20release%20(signed)_Redacted-Rel.pdf - Statement of party representatives to NTSB investigation - Textron aviation (item 11, PDF, 1 page, 90 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16631805&FileExtension=pdf&FileName=Textron%20Party%20Form%20-%20CEN23LA418_Redacted-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.