# NTSB WPR20LA288: Cessna 210, N9540T, Chino, CA, August 26, 2020

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Class 3 · Limited · Final report
- Date: August 26, 2020, 08:20 local (15:20 UTC)
- Place: Chino, CA
- Coordinates: 33.974723, -117.63639 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=33.9747&lon=-117.6364&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Defining event: [Landing: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 3
- NTSB office: Western Pacific Region
- Parties: FAA
- NTSB case key (mKey): 101866
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR20LA288
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/101866/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=101866
- Page: https://openairdocs.org/ntsb/WPR20LA288

## Probable cause

The failure of the engine-driven hydraulic pump, which resulted in the main landing gear not fully extending and locking into place during landing. Contributing to the accident was the failure of the emergency gear extension system for reasons that could not be determined.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Hydraulic power system: pump, main](https://openairdocs.org/ntsb-findings/01022913): Aircraft › Aircraft systems · Damaged/degraded (probable cause); cases with it: [Cessna 210, 1 case](https://openairdocs.org/ntsb-findings/01022913/cases.md?model=2073402), [All aircraft, 7 cases](https://openairdocs.org/ntsb-findings/01022913/cases.md)
- [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined; cases with it: [Cessna 210, 6 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=2073402), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md)
- [Landing gear system: gear extension and retract sys](https://openairdocs.org/ntsb-findings/01023230): Aircraft › Aircraft systems · Inoperative; cases with it: [Cessna 210, 6 cases](https://openairdocs.org/ntsb-findings/01023230/cases.md?model=2073402), [All aircraft, 416 cases](https://openairdocs.org/ntsb-findings/01023230/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Landing: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event); cases with it: [Cessna 210, 6 cases](https://openairdocs.org/ntsb-events/330/sequence.md?model=2073402), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md)
- [Landing: Landing gear collapse](https://openairdocs.org/ntsb-events/094); cases with it: [Cessna 210, 6 cases](https://openairdocs.org/ntsb-events/094/sequence.md?model=2073402), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md)

## Analysis

The pilot reported that the accident flight was the first flight since the airplane had undergone recent landing gear maintenance. While in the airport traffic pattern, he extended the landing gear; however, he noticed that it would not lock into the down position. Despite multiple attempts to cycle the landing gear, which included using the emergency landing gear extension procedure, he was unable to obtain a positive down and locked indication. While landing, both main landing gear collapsed and the left wing and left horizontal stabilizer impacted the runway surface, which resulted in substantial damage to the left elevator and horizontal stabilizer. Postaccident examination of the airplane revealed that the engine-driven hydraulic pump was not operational. No mechanical damage was observed within the engine’s accessory case. No evidence of any preexisting mechanical malfunction was observed with the airframe or emergency gear extension system. Examination of the engine-driven hydraulic pump revealed a torn section of an oil seal that surrounded the pump drive shaft. The oil seal was hard, brittle, and torn, which resulted in an oil leak that prevented the pump from holding pressure, which likely prevented the landing gear from fully extending and locking into place during landing. The reason for the emergency gear extension system not functioning could not be determined.

## Factual narrative

On August 26, 2020, about 0815 Pacific daylight time, a Cessna 210, N9540T, was substantially damaged when it was involved in an accident near Chino, California. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that the accident flight was the first flight since the airplane had undergone landing gear maintenance. While in the airport traffic pattern, he extended the landing gear; however, he noticed that it would not lock into the down position despite multiple attempts to cycle the landing gear, which included using the emergency landing gear extension procedure. The pilot said that he by twisted the landing gear extension handle to the left to unlock, pulled the handle out, and pumped it vertically up and down about 50 times with zero resistance. The pilot was unable to obtain a positive down and locked indication. The pilot stated that during landing on runway 26R, both main landing gear collapsed, the left wing and left horizontal stabilizer impacted the runway surface, and the airplane came to rest upright on the runway. Postaccident examination of the airplane by a Federal Aviation Administration inspector revealed that the left horizontal stabilizer and elevator were substantially damaged. Subsequent examination of the landing gear revealed that the landing gear power pack fluid level was about 12 ounces low from full, and the engine-driven hydraulic pump was not operational. No issues were noted with the emergency gear extension system. The airplane was placed on jacks and a hydraulic mule was attached to the hydraulic system. The landing gear extended and locked in place normally. The landing gear was retracted, and the emergency landing gear extension system was operated, and the landing gear extended and locked into place. The engine-driven hydraulic pump was removed from the engine, and the crankshaft was rotated by hand using the propeller. No evidence of any mechanical damage was observed to the engine accessory case. A visual inspection of the hydraulic pump revealed a torn section of a seal that surrounded the pump drive shaft. Further examination of the engine-driven hydraulic pump at a repair facility revealed that the load spring was misshaped, and the oil seal was hard, brittle, and torn, which resulted in an oil leak and the pump unable to hold pressure.

## Aircraft

- Registration: [N9540T](https://openairdocs.org/aircraft/N9540T), registered now, S/N 57340, built 1960 (OpenAirDocs)
- Reported make and model: Cessna 210 (Undesignat)
- Registry model: [Cessna 210](https://openairdocs.org/model/cessna-210) (registry code 2073402) (OpenAirDocs)
- Registry engine: [Continental I0-470 series](https://openairdocs.org/engine/continental-i0-470-series) (registry code 17027, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 57340
- Year built: 1960
- Airframe hours: 1173.3
- Engines: Continental IO-470 SERIES reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, March 17, 2020
- Departed: CNO, Chino, CA
- Destination: CNO, Chino, CA
- Airport: CNO, Chino, runway 26R, 4,858 × 150 ft, asphalt
- Equipment: Electronic primary flight display, ADS-B, Stall warning system

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 68; injuries: none; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review July 28, 2020; seat: single

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 9 statute miles
- Lowest ceiling: none
- Temperature: 77 °F, dew point 61 °F
- Altimeter: 29.81 inHg
- Observed at: KCNO

## 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 20200826016049A](https://openairdocs.org/incident/20200826016049A), Aug 26, 2020: Cessna 210, Chino, CA, Substantial damage. N9540T left Chino, and the pilot put the landing gear handle in the up position, nose gear didn't move and the main gear did not retract. Pilot recycled gear…

## Docket (9 files)

The files NTSB released with the investigation on July 8, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=101866. 5.8 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 10 pages, 610 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11688858&FileExtension=pdf&FileName=WPR20LA288%20NTSB%206120%20(Pilot)_Redacted-Rel.pdf
- Record of e-mail correspondence (pilot) (item 2, PDF, 1 page, 209 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14144921&FileExtension=pdf&FileName=Record%20of%20e-mail%20correspondence%20(Pilot)-Rel.pdf
- Record of phone conversation (pilot) (item 3, PDF, 1 page, 158 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11961306&FileExtension=pdf&FileName=Record%20of%20phone%20conversation%20(Pilot)-Rel.pdf
- Records of e-mail correspondence with maintenance facility (item 4, PDF, 3 pages, 200 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11689403&FileExtension=pdf&FileName=Records%20of%20e-mail%20correspondence%20with%20maintenance%20facility-Rel.pdf
- Record of e-mail correspondence anp exam (item 5, PDF, 2 pages, 167 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11688716&FileExtension=pdf&FileName=Record%20of%20e-mail%20correspondence%20(ANP%20findings)-Rel.pdf
- Hydraulic pump exam (item 6, PDF, 1 page, 444 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11835178&FileExtension=pdf&FileName=Pump%20exam_Redacted-Rel.pdf
- Hydraulic pump evidence control form (item 7, PDF, 2 pages, 51 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11844164&FileExtension=pdf&FileName=Hydraulic%20Pump%20Evidence%20Control%20Form_Redacted-Rel.pdf
- Release of aircraft wreckage, NTSB form 6120.15 (item 8, PDF, 1 page, 2.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11844045&FileExtension=pdf&FileName=Aircraft%20Release_Redacted-Rel.pdf
- Photo array (item 9, PDF, 5 pages, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11842966&FileExtension=pdf&FileName=Photo%20Array-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.

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