# NTSB CEN10LA302: Beech C90, N20, Fort Worth, TX, June 3, 2010 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: June 3, 2010, 14:30 local (19:30 UTC) - Place: Fort Worth, TX - Coordinates: 32.987777, -97.318885 - Nearby events: https://openairdocs.org/map.md?lat=32.9878&lon=-97.3189&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-flare/touchdown: Landing gear collapse](https://openairdocs.org/ntsb-events/094) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report April 12, 2011 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA Flight Standards District Office - NTSB case key (mKey): 76227 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN10LA302 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/76227/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=76227 - Page: https://openairdocs.org/ntsb/CEN10LA302 ## Probable cause The failure of the nose gear actuator due to insufficient lubrication of the nut assembly threads. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: landing gear actuator](https://openairdocs.org/ntsb-findings/01023233): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [All aircraft, 54 cases](https://openairdocs.org/ntsb-findings/01023233/cases.md) - [Fluids: grease](https://openairdocs.org/ntsb-findings/01071035): Aircraft › Fluids/misc hardware · Fluid level (probable cause); cases with it: [All aircraft, 6 cases](https://openairdocs.org/ntsb-findings/01071035/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330); cases with it: [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md) - [Landing-flare/touchdown: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event); cases with it: [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis As the landing gear was extended, the flightcrew heard a loud "bang" and observed a “Gear Unsafe” indication. After making a low pass, tower personnel reported that the main gear appeared to be down but that the nose gear was only partially extended. The certificated flight instructor raised the landing gear and made another low pass. Tower personnel said the main gear was up, but the nose gear was still only partially extended. The flightcrew elected to return to their home base and land. As speed dissipated, the nose gear folded and the airplane slid to a stop. A postaccident examination revealed that the nose gear actuator had failed due to insufficient lubrication of the nut assembly threads. The manufacturer recommends that the actuator be overhauled or replaced every 8000 cycles, or 6 years, whichever occurs first. At this time, the screw and nut assembly is to be greased. The failed actuator had accrued 1,576 cycles and 951.2 hours time-in-service. The maintenance manual does not require in-service lubrication of landing gear actuator. ## Factual narrative On June 3, 2010, approximately 1430 central daylight time, a Beech C90, N20, registered to and operated by the Federal Aviation Administration, was substantially damaged when the nose landing gear collapsed on landing at Alliance Fort Worth Airport (AFW), Fort Worth, Texas. Visual meteorological conditions (VMC) prevailed at the time of the accident. The training flight was being conducted under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91 without a flight plan. The two pilots on board the airplane were not injured. The local flight originated at 1305 from AFW. The purpose of the flight was to maintain inspector currency. After completion of air work, the airplane proceeded to Waco (ACT), Texas, where takeoffs and landings were to be made. As the landing gear was extended during the first approach, the crew heard a loud "bang" and observed a GEAR UNSAFE indication. After making a low pass ACT tower reported the main gear appeared to be down, but the nose gear was only partially extended. The instructor raised the landing gear and made another low pass. Tower personnel said the main gear was up, but the nose gear was still only partially extended. The crew returned to AFW and, after consulting with FSDO, Oklahoma City maintenance, and Hawker Beechcraft, the decision was made to land the airplane on runway 34L. As speed dissipated, the nose gear folded and the airplane slid to a stop. The nose wheel bulkhead was damaged. Post-accident examination revealed the nose gear actuator (p/n 50-820208-5, s/n 93963) had failed. The actuator was sent to Aerospace Turbine Rotables, Inc., Wichita, Kansas, where it was disassembled and examined. According to their Teardown and Inspection Report, “The most probable root cause of the actuator failure was relevant to insufficient lubrication of the nut assembly threads.” According to FAA, Hawker Beechcraft maintenance manual does not require in-service lubrication of landing gear actuator. The mechanical actuator is suppose to be overhauled or replaced every 8000 cycles, or 6 years, whichever occurs first. During this time, the screw and nut assembly is to be greased. FAA said that the actuator on N20 accrued 1,576 and 951.2 hours time-in-service before it failed. Hawker Beechcraft confirmed that there was no requirement for lubricating the landing gear actuator. Consequently, the company reported it had implemented a change to the King Air maintenance manual that will include a lubrication requirement for the screw and nut assembly. ## Aircraft - Registration: N20 (not matched to a registry record) - Reported make and model: BEECH C90 - Category: Airplane - Serial number: LJ-912 - Airframe hours: 11204 - Engines: Pratt & Whitney Canada PT6A-21 550 horsepower turbo prop - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Federal Aviation Administration (ASW-280) - Registered owner: Federal Aviation Administration (ASW-280) - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, February 1, 2010 - Departed: AFW, Fort Worth, TX - Destination: AFW, Fort Worth, TX - Flight plan: IFR - Airport: AFW, Fort Worth Alliance, runway 34L, 8,220 × 150 ft, concrete ## Flight crew As NTSB recorded them. NTSB leaves out names. - Check pilot; age 71; injuries: none; flight instructor, airline transport; airplane ratings: single-engine land, multi-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review September 15, 2009; seat: right; flight hours: 15,490 total, 150 in this make and model, 15,138 as pilot in command, 116 in the last 90 days, 47 in the last 30 days, 3 in the last 24 hours - Pilot; age 68; injuries: none; flight instructor, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review January 14, 2009; seat: left; flight hours: 17,500 total, 100 in this make and model, 17,200 as pilot in command, 20 in the last 90 days, 5 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 100° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 90 °F, dew point 66 °F - Altimeter: 29.75 inHg - Observed at: AFW ## 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 20100603005199A](https://openairdocs.org/incident/20100603005199A), Jun 3, 2010: Beech C90, Fort Worth, TX, Substantial damage. During routine training landing pilot reported loud bang during landing gear extension . Tower told pilot that gear was not fully extended .pilot hand cranked… ## Docket (12 files) The files NTSB released with the investigation on October 26, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=76227. 3.1 MB in all. - NTSB Form 6120.1-2, Pilot-Operator Aircraft Accident Report (item 1, .PDF, 518 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40334086&FileExtension=.PDF&FileName=NTSB%20Form%206120.1-2,%20Pilot-Operator%20Aircraft%20Accident%20Report-Redacted.PDF - Aerospace Turbine Rotables, Inc., Teardown Report (item 2, .PDF, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40337455&FileExtension=.PDF&FileName=Aerospace%20Turbine%20Rotables,%20Inc.,%20Teardown%20Report-Redacted.PDF - Weather Reports and Records (item 3, .PDF, 19 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40336619&FileExtension=.PDF&FileName=Weather%20Reports%20and%20Records-Master.PDF - Nose Landing Gear Installation (item 4, .PDF, 33 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40337457&FileExtension=.PDF&FileName=Nose%20Landing%20Gear%20Installation-Master.PDF - Nose Landing Gear Actuator (item 5, .PDF, 27 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40337458&FileExtension=.PDF&FileName=Nose%20Landing%20Gear%20Actuator-Master.PDF - Weather Reports and Records (item 6, .PDF, 19 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40332664&FileExtension=.PDF&FileName=Weather%20Reports%20and%20Records-Master.PDF - Photo 1. Damage to nose section of airplane. (item 7, .PDF, 56 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40332665&FileExtension=.PDF&FileName=Photo%201.%20Damage%20to%20nose%20section%20of%20airplane.-Master.PDF - Photo 2. Damage to nose section of airplane. (item 8, .PDF, 37 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40332666&FileExtension=.PDF&FileName=Photo%202.%20Damage%20to%20nose%20section%20of%20airplane.-Master.PDF - Photo 3. Damage to nose section of airplane. (item 9, .PDF, 61 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40332667&FileExtension=.PDF&FileName=Photo%203.%20Damage%20to%20nose%20section%20of%20airplane.-Master.PDF - Photo 4. Nose landing gear actuator. Note lack of grease. (item 10, .PDF, 202 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40334083&FileExtension=.PDF&FileName=Photo%204.%20Nose%20landing%20gear%20actuator.%20Note%20lack%20of%20grease.-Master.PDF - Photo 5. Threads pulled out of screw assembly. (item 11, .PDF, 230 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40334084&FileExtension=.PDF&FileName=Photo%205.%20Threads%20pulled%20out%20of%20screw%20assembly.-Master.PDF - Photo 6. Threads stuck inside screw housing. (item 12, .PDF, 223 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40334085&FileExtension=.PDF&FileName=Photo%206.%20Threads%20stuck%20inside%20screw%20housing.-Master.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.