# NTSB LAX04LA108: Cessna P210N, N4873K, Tucson, AZ, January 18, 2004 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: January 18, 2004, 05:52 local (12:52 UTC) - Place: Tucson, AZ - Coordinates: 32.116111, -110.941108 - Nearby events: https://openairdocs.org/map.md?lat=32.1161&lon=-110.9411&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report April 28, 2005 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 58679 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX04LA108 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/58679/pdf - Page: https://openairdocs.org/ntsb/LAX04LA108 ## Probable cause the failure of the electrical charging system and pilot's failure to verify that the gear was down-and-locked prior to the complete electrical system failure. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, cruise - light condition - night (contributing factor) - electrical system - failure (cause) - Main gear collapsed, landing - roll - gear down and locked - not verified, pilot in command (cause) - On ground/water collision with object, landing - roll - object - airport sign/marker ## Analysis During the landing roll, the airplane's left main landing gear collapsed and the airplane collided with a taxiway sign. While en route to his destination, the battery warning light illuminated, indicating that the electrical system was not charging. The pilot performed the emergency checklist items; however, the alternator would not reset. The pilot then reversed course to return to the departure airport. The pilot turned off all nonessential electrical equipment in an attempt to conserve battery power. The pilot extended the landing gear and 10 degrees of flaps, then turned the master switch off. The pilot later told responding airport police officers that he did not wait for the gear enunciator lights to turn green indicating that the landing gear was down-and-locked before shutting off the electrical master switch. As the airplane approached the airport, the pilot turned the master switch back on, but the battery had fully drained. The pilot said that he was unsure if the gear were down and locked so on final approach he pumped the emergency gear extension handle. During the landing roll, the left main gear collapsed. Post accident examination of the electrical system revealed that the main alternator field wire and power wire terminals were broken due to a vibration of the alternator. The alternator was not secure on its mounting bracket due to fretting on the forward portion of the alternator bracket housing, which had enlarged the holes into an oval shape. When the alternator and bracket were touched, the entire assembly would move. ## Factual narrative On January 18, 2004, at 0552 mountain standard time, a Cessna P210N, N4873K, experienced a collapse of the left main landing gear during the landing roll at the Tucson International Airport (TUS), Tucson, Arizona. The pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The private pilot was not injured; the airplane sustained substantial damage. The flight departed Tucson at 0440, en route to Dallas Love Field (DAL), Dallas, Texas. Visual meteorological conditions prevailed, and no flight plan had been filed. The Tucson Airport Police interviewed the pilot immediately following the accident. He reported that en route, a light illuminated indicating that the battery was not charging. The pilot competed the emergency checklist procedures, but the light continued to illuminate. After lowering the landing gear and the flaps, the pilot turned the master switch to the "OFF" position, in order to conserve power. He did not wait for the "green light," indicating that the gear was in a down and locked position. The pilot landed without difficulty. However, during the landing roll, the right main gear collapsed, and the airplane collided with a taxiway sign. The pilot submitted a written statement. While en route to Dallas, 30 miles east of Benson, Arizona, the low battery light illuminated. He verified that the alternator was not working and it would not reset. He turned the airplane in the direction of Tucson and declined landing at Benson because he had not landed there before. He advised Tucson approach control of his intentions and then turned the master switch into the "OFF" position. He continued to Tucson at an altitude of 17,500 feet mean sea level (msl). During a descent to 15,000 feet msl, the landing gear was lowered as the pilot searched for the airport. He again turned the radio master switch on and the global positioning system (GPS) indicated he was flying over the runways. The Tucson International Air Traffic Control Tower (ATCT) advised him to fly heading 140; he turned and located runway 11L. He then extended the flaps and all electrical power was lost. The airplane was positioned on final for runway 11L and a 360-degree turn was completed because the airplane's altitude was too high. As the pilot turned onto final, the emergency gear extension lever was "pumped a few times" until he was certain the gear was fully extended. The airplane touched down at 70 knots. During the landing roll, the left main gear collapsed. The electrical system was examined at Premier Aviation on February 25, 2004, under the auspices of a Federal Aviation Administration (FAA) inspector. The alternator, although it appeared securely attached, would move when it was touched. The technician reported that a 9-inch bolt secured the alternator to the engine mount by a bracket. A shorter bolt assisted in tensioning the alternator belt. Each of the bolts was secured in their respective positions. The longer bolt fit through the alternator housing and was clamped through the use of bushings. Although the longer bolt was torqued against the bushings, it was not secure in the housing due to aluminum wear on the forward portion of the housing. The forward portion of the housing was an oval shape. A vibration resulted, and the field and main power wires' terminals became disconnected. The tension of the alternator belt was normal. On March 26, 2004, the bolts, bushings, and housing were reexamined. The housing diameter was measured at 0.8777-inch. The bolt diameter was measured to be 0.4373-inch. The bushings on the aft portion of the bolt housing measured 0.7468-inch for the outer diameter and 0.4601-inch for the inner diameter. The forward bushing inner diameter measured 0.5287-inch. The forward bushing was egg shaped and stuck in the bolt housing. Fretting corrosion was present along the surface of the forward housing. ASA Dictionary of Aeronautical Terms defines fretting corrosion as a form of corrosion between two surfaces which have a slight amount of relative motion between them. The protective oxide coating that forms on aluminum or magnesium alloys is rubbed away by the movement of the parts. New oxides must be continually formed to replace those that are worn away. ## Aircraft - Registration: N4873K (not matched to a registry record) - Reported make and model: Cessna P210N - Category: Airplane - Serial number: P21000352 - Airframe hours: 3234.1 - Engines: Continental TSIO-520-P7B 310 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: James Garrett - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 1, 2003 - Departed: TUS, Tucson, AZ - Destination: DAL, Dallas, TX - Airport: TUS, Tucson International, runway 11L, 10,996 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 61; injuries: none; private; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; last flight review March 4, 2003; seat: left; flight hours: 2,462 total, 178 in this make and model, 2,462 as pilot in command, 69 in the last 90 days, 38 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Night - Wind: 150° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 39 °F, dew point 34 °F - Altimeter: 30.13 inHg - Observed at: TUS ## 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 20040118001529A](https://openairdocs.org/incident/20040118001529A), Jan 18, 2004: Cessna P210N, Tucson, AZ, Substantial damage. (-23) Pilot stated that he had taken off from Tucson at 4:00 am enroute to Texas when he experienced a total electrical failure. He returned to Tucson,… 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.