# NTSB WPR22LA080: Walter Tachiki Tachiki 750 Cruzer, N145WT, Spanish Fork, UT, January 14, 2022 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Class 3 · Limited · Final report - Date: January 14, 2022, 12:48 local (19:48 UTC) - Place: Spanish Fork, UT - Coordinates: 40.130918, -111.65227 - Nearby events: https://openairdocs.org/map.md?lat=40.1309&lon=-111.6523&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration, Viking Aircraft Engines - NTSB case key (mKey): 104529 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR22LA080 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/104529/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=104529 - Page: https://openairdocs.org/ntsb/WPR22LA080 ## Probable cause A partial loss of engine power due to an obstructed catalytic converter, which most likely resulted from the pilot’s failure to properly repair or replace it after it was likely damaged during a previous incident. Contributing to the accident was the pilot’s failure to maintain adequate airspeed during the forced landing, which led to an exceedance of the airplane’s critical angle-of-attack and an aerodynamic stall. ## 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) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause) - [Performance/control parameters: angle of attack](https://openairdocs.org/ntsb-findings/01062042): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause) - [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause) - [Maintenance: repair](https://openairdocs.org/ntsb-findings/02062015): Personnel issues › Task performance · Pilot ## Analysis The pilot departed on the local accident flight after having repaired his airplane following a landing incident that occurred 18 months earlier. Shortly after departure, he observed a partial loss of engine power and was unable to maintain altitude. He immediately returned to the airport, but, while maneuvering toward the runway, he made a tight left turn, which likely resulted in an exceedance of the airplane’s critical angle of attack and an accelerated stall. The airplane entered a nose-down dive and impacted a rooftop. Postaccident examination of the airframe did not reveal any preimpact mechanical anomalies that could have precluded the pilot from controlling the airplane. Examination of the engine revealed that most of the internal components were likely operational at the time of impact. However, the catalytic converter contained several broken pieces of ceramic substrate that had separated during the previous accident. As there were no other preimpact mechanical anomalies with the engine, it is likely that broken substrate blocked the engine exhaust gas path following combustion, which resulted in a partial loss of engine power during the accident flight. The pilot straightened the bent exhaust tailpipe after the landing incident and re-welded the catalytic converter. However, he did not inspect, repair, or replace the catalytic converter before the accident flight even after debris was emitted from the tailpipe on subsequent engine starts. ## Factual narrative On January 14, 2022, about 1248 mountain standard time, an experimental amateur-built Zenith CH 750 (Cruzer), N145WT, was substantially damaged when it was involved in an accident near Spanish Fork, Utah. The pilot was seriously injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that this was his first flight in the accident airplane since he was involved in a landing incident that took place in the same airplane about 18 months earlier. Before the accident flight, he fast-taxied the airplane down the runway to check the operability of the flight control system and engine controls and did not observe any anomalies. Shortly after takeoff when the airplane was about 5 nautical miles away from the airport, the pilot observed a slow decay in engine power and was suddenly unable to maintain altitude. He immediately started a left turn to return to the airport and he advanced the throttle to the full power setting but was unsuccessful in restoring power to the engine. According to a witness, the airplane entered a steep left turn at approximately 80 ft above ground level that quickly transitioned into a nose-down dive before it disappeared from view behind obstacles. The pilot stated that the airplane slowed during the turn and impacted the roof of a building. The airplane sustained substantial damage to the fuselage and both wings. The airplane was equipped with a Honda VTEC automotive engine. Postaccident examination revealed that mechanical continuity was established throughout the rotating group, reduction gearbox, engine flywheel, crankshaft and accessory section as the crankshaft was manually by hand rotated at the prop hub. Thumb compression was achieved at all four cylinders. Examination of the cylinders combustion chamber interior components using a lighted borescope revealed normal piston face and cylinder wall signatures, and no indications of a catastrophic engine failure. The ignition coils were tightly secured to their respective spark plugs and the ECU harnesses were connected to each coil. The coils were all normal in appearance and did not exhibit any debris or discoloration when visually inspected. All four of the spark plugs were gray in appearance, consistent with normal wear and the center electrodes were unremarkable. A postaccident engine run did not reveal any preimpact anomalies. An inspection of the elevator, flaperon, and rudder controls did not reveal any abnormalities. The engine was equipped with a catalytic converter that was used to convert toxic exhaust gases produced during combustion. The converter was comprised of a honeycomb ceramic substrate secured within the case that directed the exhaust gas airflow towards the tailpipe. Although the converter remained securely attached to the engine case, the bottom half of the internal ceramic substrate had broken into numerous large pieces. Figure 1. Interior catalytic converter substrate as observedthrough tailpipe Figure 2. Top and bottom halves of catalytic converter with exposed substrate (top is on the left side, bottom on the right side) The pilot reported that following a landing incident that occurred 18 months before the accident, he noticed gray fragments coming from the tailpipe, which was bent as a result of impact damage. The pilot subsequently repaired the tailpipe by straightening it and re-welded it back to the catalytic converter. The pilot reported he noticed small white particles come out of the tailpipe the first time he started the engine after the incident and then once again a piece that was the size of a quarter to a half-dollar came out on the second or third engine start. He did not inspect, repair, or replace the catalytic converter before the accident flight. According to a representative of the engine manufacturer who reviewed the engine examination report, as backpressure is required for the engine to function, an obstructed exhaust can affect engine backpressure and result in a partial loss of engine power. The engine kit manufacturer, and company responsible for retrofitting the automotive engine for aviation applications, also stated that an obstructed catalytic converter could prevent the engine from producing power. ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event) - [Approach-VFR pattern base: Loss of control in flight](https://openairdocs.org/ntsb-events/240) - [Approach-VFR pattern base: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241) ## Aircraft - Registration: [N145WT](https://openairdocs.org/aircraft/N145WT), registered now, S/N WTI, built 2019 (OpenAirDocs) - Reported make and model: WALTER TACHIKI TACHIKI 750 CRUZER - Registry model: [Walter Tachiki TACHIKI 750 CRUZER](https://openairdocs.org/model/walter-tachiki-tachiki-750-cruzer) (registry code 05637KK) (OpenAirDocs) - Registry engine: [Honda VTECH](https://openairdocs.org/engine/honda-vtech) (registry code 33795, 4 cycle) (OpenAirDocs) - Category: Airplane - Serial number: WTI - Year built: 2019 - Engines: Honda VTEC 140 hp reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, January 13, 2022 - Departed: SPK, Spanish Fork, UT - Airport: SPK, Spanish Fork Muni/Woodhouse Fld - Equipment: Electronic multifunction display, Electronic primary flight display, Electronic flight bag or handheld device, Data recorder, Angle of attack indicator, Satellite tracking device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 77; injuries: serious; private; airplane ratings: single-engine land; medical: unknown; seat: left; flight hours: 66 total, 3.7 in this make and model ## Weather - Conditions: Visual (VMC), Day - Visibility: 6 statute miles - Temperature: 37 °F, dew point 27 °F - Altimeter: 30.45 inHg - Observed at: KPVU, 6 nm away - METAR: KPVU 141956Z VRB06KT 6SM HZ FEW060 03/M03 A3045 RMK AO2 SLP328 T00331028 ## 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 20220114000639A](https://openairdocs.org/incident/20220114000639A), Jan 14, 2022: Walter Tachiki TACHIKI 750 CRUZER, Spanish Fork, UT, Substantial damage. The pilot in command (PIC) started N145WT with intent to takeoff on runway 30 at the Spanish Fork-Springville municipal airport (U77). During takeoff, the PIC… ## Docket (11 files) The files NTSB released with the investigation on June 8, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=104529. 23.4 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 6.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15051313&FileExtension=pdf&FileName=6120%201_Redacted-Rel.pdf - Record of conversation, engine manufacturer (item 2, PDF, 1 page, 118 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14610322&FileExtension=pdf&FileName=Record%20of%20Conversation%20honda-Rel.pdf - Record of conversations, witnesses (item 3, PDF, 2 pages, 157 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14607386&FileExtension=pdf&FileName=record%20of%20convos%20witnesses-Rel.pdf - Email correspondence with engine kit manufacturer (item 4, PDF, 8 pages, 153 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15051323&FileExtension=pdf&FileName=email%20correspondence%20with%20engine%20kit%20manufacturer_Redacted-Rel.pdf - Email correspondence with pilot (item 5, PDF, 4 pages, 203 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14610037&FileExtension=pdf&FileName=email%20correspondence%20with%20pilot_Redacted-Rel.pdf - Witness statements from FAA (item 6, PDF, 2 pages, 171 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14607376&FileExtension=pdf&FileName=witness%20statements_Redacted-Rel.pdf - Aircraft logbook excerpt (item 7, PDF, 9 pages, 5.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14609230&FileExtension=pdf&FileName=Aircraft%20log_Redacted-Rel.pdf - NTSB wreckage examination report (item 8, PDF, 13 pages, 2.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14607510&FileExtension=pdf&FileName=NTSB%20Wreckage%20Examination%20Report-Rel.pdf - Statement of party representatives to NTSB investigation (item 9, PDF, 1 page, 4.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14608039&FileExtension=pdf&FileName=Signed%20for%20NTSB_Redacted-Rel.pdf - Accident photographs (item 10, PDF, 2 pages, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14610027&FileExtension=pdf&FileName=Accident%20Photographs-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 11, PDF, 1 page, 1.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14634200&FileExtension=pdf&FileName=Release%20of%20wreckage_Redacted-Rel.pdf From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date; 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.