# NTSB CEN20LA140: Beech 35, N9883R, Seguin, TX, April 1, 2020 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: April 1, 2020, 13:10 local (18:10 UTC) - Place: Seguin, TX - Coordinates: 29.501098, -97.995338 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=29.5011&lon=-97.9953&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing: Runway excursion](https://openairdocs.org/ntsb-events/300) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: Textron Aviation, Continental Aerospace Technologies, FAA San Antonio FSDO - NTSB case key (mKey): 101143 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN20LA140 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/101143/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=101143 - Page: https://openairdocs.org/ntsb/CEN20LA140 ## Probable cause The pilot’s mismanagement of airspeed and glidepath during approach for a precautionary landing, which resulted in a runway excursion and a collision with a fence. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Beech M35, 2 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=1151526), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Performance/control parameters: surface speed/braking](https://openairdocs.org/ntsb-findings/01062045): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Beech M35, 1 case](https://openairdocs.org/ntsb-findings/01062045/cases.md?model=1151526), [All aircraft, 238 cases](https://openairdocs.org/ntsb-findings/01062045/cases.md) - [Engine (reciprocating)](https://openairdocs.org/ntsb-findings/01058500): Aircraft › Aircraft power plant · Unknown/Not determined; cases with it: [Beech M35, 1 case](https://openairdocs.org/ntsb-findings/01058500/cases.md?model=1151526), [All aircraft, 497 cases](https://openairdocs.org/ntsb-findings/01058500/cases.md) - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot; cases with it: [Beech M35, 1 case](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=1151526), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md) - [Object/animal/substance: fence/fence post](https://openairdocs.org/ntsb-findings/03022047): Environmental issues › Physical environment · Contributed to outcome (probable cause); cases with it: [Beech M35, 1 case](https://openairdocs.org/ntsb-findings/03022047/cases.md?model=1151526), [All aircraft, 313 cases](https://openairdocs.org/ntsb-findings/03022047/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Unknown or undetermined](https://openairdocs.org/ntsb-events/000); cases with it: [Beech M35, 2 cases](https://openairdocs.org/ntsb-events/000/sequence.md?model=1151526), [All aircraft, 1,703 cases](https://openairdocs.org/ntsb-events/000/sequence.md) - [Approach-VFR pattern final: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Beech M35, 3 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=1151526), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing: Runway excursion](https://openairdocs.org/ntsb-events/300) (defining event); cases with it: [Beech M35, 1 case](https://openairdocs.org/ntsb-events/300/sequence.md?model=1151526), [All aircraft, 3,643 cases](https://openairdocs.org/ntsb-events/300/sequence.md) - [Landing: Collision during takeoff/land](https://openairdocs.org/ntsb-events/490); cases with it: [Beech M35, 1 case](https://openairdocs.org/ntsb-events/490/sequence.md?model=1151526), [All aircraft, 1,309 cases](https://openairdocs.org/ntsb-events/490/sequence.md) ## Analysis During the initial climb, the airplane’s No. 3 cylinder indicated a cylinder head temperature (CHT) about 60° cooler than the other five cylinders. At 1,000 ft above ground level, the first power reduction was made from takeoff power to 2,500 rpm and 25 inches manifold pressure. The pilot reported a “normal reduction” in fuel flow was made with the mixture control. Immediately, the pilot heard and felt a loud, continuous “rhythmic banging” noise. The pilot noted the No. 3 cylinder CHT had reduced to 220° F; however, all other engine instrument indications remained in the normal range, and the engine still produced power. The pilot decided to return to the airport and land. Once established on the final approach for the runway, the pilot concluded that the airplane was "high and fast.” The pilot reported he was committed to the landing even though he knew he would land "long and hot." After the touchdown, the rollout was “completely under control,” but the groundspeed was “fast.” The airplane crossed the end of the runway and traveled past the runway overrun area. The airplane came to a stop after impact with a fence. The pilot reported the engine continued to run until he shut it down. The airplane sustained substantial damage to the right wing. A postaccident examination of the engine was performed and a small amount of metal was found in the oil filter; no other preimpact anomalies were noted with the engine. The cause of the noise as reported by the pilot and the low No. 3 cylinder CHT could not be determined based on the available evidence. The accident is consistent with the pilot mismanaging his airspeed and glidepath during approach, which resulted in a precautionary landing too far down the runway at too high an airspeed to stop on the remaining runway. ## Factual narrative On April 1, 2020, about 1310 central daylight time, a Beech M35 airplane, N9883R, sustained substantial damage when it was involved in an accident near Sequin, Texas. The pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, on the initial climb, the No. 3 cylinder indicated a cylinder head temperature (CHT) about 60° cooler than the other five cylinders. At 1,000 ft above ground level, the first power reduction was made from takeoff power to 2,500 rpm and 25 inches manifold pressure. The pilot reported a “normal reduction” in fuel flow was made with the mixture control. Immediately, the pilot heard and felt a loud, continuous “rhythmic banging” noise. The pilot noted the No. 3 cylinder CHT had reduced to 220° F; however, all other engine instrument indications remained in the normal range, and the engine still produced power. The pilot decided to return to the departure airport and land. The pilot assessed that, if a total loss of engine power occurred, there was sufficient altitude and airspeed to turn base and final legs for a landing on the departure runway. He also planned a touchdown point on the grass runway beyond the normal touchdown point. Once established and set up on the final approach for runway 14, the pilot concluded that the airplane was "high and fast" and there was insufficient altitude to perform any descending turns. The pilot reported he was committed to the landing even though he knew he would land "long and hot." After the touchdown on the dry grass, the rollout was “completely under control,” but the groundspeed was “fast.” The airplane crossed the end of the runway and traveled past the runway overrun area. The airplane impacted a small metal farm fence and came to rest upright. The outboard portion of the right wing impacted a small tree trunk and rotated the airplane 180° back toward the runway, which caused substantial damage. The pilot reported the engine continued to run until he shut it down. The pilot and passenger were able to egress from the airplane without further incident. The pilot reported he departed with 52 gallons of fuel onboard; there was fuel present in all four fuel tanks, and there were no fuel leaks after the accident. A postaccident examination of the engine was performed and a small amount of unidentified debris was present underneath the fuel manifold valve screen. No other preimpact anomalies were noted with the engine. The airframe was released to salvage before the investigation was able to complete a detailed examination. This engine’s No. 3 cylinder is located on the right side of the engine, in the middle, between the No. 5 cylinder (forward), and the No. 1 cylinder (aft). The Federal Aviation Administration (FAA)-approved Continental Motors Operator’s Manual for the IO-470 series engine discusses CHT and states in part: Cooling of cylinders depends on aircraft baffles being maintainedproperly fit to the cylinder heads and barrels and other joints in the pressure compartment being tight so as to force air between the cylinder fins. Proper cooling also depends on operation practices. The recommended power setting (RPM and manifold pressure) should not be exceeded for long periods. Fuel and air mixture ratio also affects cylinder temperature. The FAA Airplane Flying Handbook (FAA-H-8083-3B) discusses three likely probable causes of a low CHT and states Excessive cowl flap opening. Excessively rich mixture. Extended glides without clearing engine. This document also lists corrective actions for the three likely probable causes of a low CHT and states: Adjust cowl flaps. Adjust mixture control. Clear engine long enough to keep temperatures at minimum range. ## Aircraft - Registration: [N9883R](https://openairdocs.org/deregistered/N9883R-2021-09-04), registration cancelled 2021-09-04, S/N D-6454, built 1960 (OpenAirDocs) - Reported make and model: Beech 35 (M35) - Registry model: [Beech M35](https://openairdocs.org/model/beech-m35) (registry code 1151526) (OpenAirDocs) - Registry engine: [Continental I0-470 series](https://openairdocs.org/engine/continental-i0-470-series) (registry code 17027, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: D-6454 - Year built: 1960 - Airframe hours: 4727.6 - Engines: Continental Motors IO-470-C 250 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Utility - Last inspection: Annual, January 15, 2020, 0 hours before - Departed: 0TX6, Seguin, TX - Airport: 0TX6, Elm Creek Airpark, runway 14, 1,925 × 75 ft, grass/turf - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 76; injuries: none; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: basicmed, without waivers/limitations; last flight review February 20, 2020; seat: left; restraint: lap only; flight hours: 8,070 total, 250 in this make and model, 5 in the last 90 days, 5 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 160° at 6 knots - Visibility: 10 statute miles - Temperature: 72 °F, dew point 50 °F - Altimeter: 30.00 inHg - Observed at: KRND, 14 nm away - METAR: KRND 011756Z AUTO 16006KT 10SM FEW150 FEW180 22/10 A3000 RMK AO2 SLP155 T02180097 10218 20104 57013 ## 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 20200401008949A](https://openairdocs.org/incident/20200401008949A), Apr 1, 2020: Beech M35, Seguin, TX, Substantial damage. During normal climb out, pilot observed that #3 cylinder was reading 600 lower than the other 5 at 1000' AGL. When initial power reduction was made, loud… ## Docket (5 files) The files NTSB released with the investigation on February 7, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=101143. 19.1 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 10 pages, 4.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12481160&FileExtension=pdf&FileName=NTSB%20Form%206120_1%20Redacted-Rel.pdf - Accident photographs (item 2, PDF, 8 pages, 5.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12549736&FileExtension=pdf&FileName=Accident%20Photos-Rel.pdf - NTSB engine examination report (item 3, PDF, 8 pages, 4.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12481381&FileExtension=pdf&FileName=NTSB%20Engine%20Examination%20Report-Rel.pdf - N9883R - airplane and maintenance records (courtesy of mclarens aviation) (item 4, PDF, 4 pages, 4.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12484194&FileExtension=pdf&FileName=N9883R%20-%20Airplane%20and%20Maintenance%20Records%20Redacted-Rel.pdf - NTSB party member forms (item 5, PDF, 2 pages, 521 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12480955&FileExtension=pdf&FileName=NTSB%20Party%20Member%20Forms%20Redacted-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.