# NTSB CHI04LA046: Beech 95-B55, N221Q, St. Paul, MN, December 22, 2003 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: December 22, 2003, 16:49 local (22:49 UTC) - Place: St. Paul, MN - Coordinates: 44.934444, -93.059997 - Nearby events: https://openairdocs.org/map.md?lat=44.9344&lon=-93.0600&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report June 2, 2004 - Report: Approved by Office Director - Parties: Federal Aviation Administration - Minneapolis FSDO - NTSB case key (mKey): 58567 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI04LA046 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/58567/pdf - Page: https://openairdocs.org/ntsb/CHI04LA046 ## Probable cause The failure of the worm drive bearing that resulted in the failure of the landing gear extension/retraction gearbox, which ultimately resulted in the extension of the landing gear not being possible. A factor to the accident was the airport sign that the airplane impacted during the wheels-up landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, approach - vfr pattern - downwind - remedial action - not successful, pilot in command(cfi) - landing gear,normal retraction/extension assembly - failure (cause) - maintenance,inspection - not performed, company maintenance personnel - Wheels up landing, landing - gear extension - not possible, pilot in command(cfi) (cause) - On ground/water collision with object, landing - object - airport sign/marker (contributing factor) ## Analysis The airplane sustained substantial damage while landing wheels-up, subsequent to the crew being unable to extend the landing gear. The certified flight instructor (CFI) stated the landing gear did not fully extend and the gear-down lighting did not illuminate while on downwind. The CFI reported they attempted to retract the landing gear, but the gear-up light did not illuminate. The CFI stated they attempted to extend the landing gear again; however, the cabin began to fill with smoke, and the gear motor and right generator circuit breakers both tripped. The CFI reported they performed the manual gear extension procedure without success. The CFI stated that "The manual gear extension handle was not catching anything and turning very loosely." The CFI reported they landed with the landing gear retracted and subsequently impacted a runway sign. Subsequent to the accident the landing gear extension/retraction system was examined while the airplane was elevated on jackstands. The landing gear did not extend using the electric or the manual gear extension procedure. The landing gear extension/retraction gearbox was disassembled for further inspection. One of the actuator worm gear bearings was found in several pieces, resulting in the worm gear being lodged between the sector gear and the gearbox housing. According to the Beech 95-B55 maintenance manual, the landing gear extension/retraction gearbox is to be replaced or overhauled every 2,000 hours. The accident airplane's gearbox assembly had accumulated 2,137 hours since the last overhaul and 6,342 hours since new. ## Factual narrative On December 22, 2003, at 1649 central standard time, a Beech 95-B55, N221Q, piloted by a certified flight instructor (CFI), sustained substantial damage while landing wheels-up on runway 31 (4,115 feet by 150 feet, dry asphalt) at the St. Paul Downtown Airport (STP), St. Paul, Minnesota. Visual meteorological conditions prevailed at the time of the accident. The CFI and his dual student reported no injuries. The instructional flight was operating under the provisions of 14 CFR Part 91 without a flight plan. The local flight departed South St. Paul Municipal Airport (SGS) at 1513. According to the CFI's written statement, during the flight they had successfully completed several landings at STP prior to returning to SGS. The CFI reported that he and his student heard a "loud noise" during the last landing gear retraction. The CFI stated the landing gear did not fully extend and the gear-down lighting did not illuminate while on downwind for runway 34 at SGS. The CFI reported they attempted to retract the landing gear, but the gear-up light did not illuminate. The CFI stated they departed the traffic pattern and began to troubleshoot the problem. The CFI reported they attempted to extend the landing gear again; however, the cabin began to fill with smoke, and the gear motor and right generator circuit breakers both tripped. The CFI stated they performed the manual gear extension procedure without success. The CFI reported that "The manual gear extension handle was not catching anything and turning very loosely." The CFI stated they performed a tower fly-by at STP so that the tower personnel could assess the landing gear position. STP tower personnel reported that the gear doors were open but the landing gear was not extended. The CFI reported they landed with the landing gear retracted and subsequently impacted a runway sign. An inspector with the Federal Aviation Administration (FAA) performed the on-scene investigation. The landing gear extension/retraction system was examined while the airplane was elevated on jackstands. The inspector was unable to extend the landing gear using the electric or the manual gear extension procedure. The landing gear extension/retraction gearbox was disassembled for further inspection. The inspector reported that one of the actuator worm gear bearings was found in several pieces, resulting in the worm gear being lodged between the sector gear and the gearbox housing. According to the Beech 95-B55 maintenance manual, the landing gear extension/retraction gearbox is to be replaced or overhauled every 2,000 hours. The accident airplane's gearbox assembly had accumulated 2,137 hours since the last overhaul and 6,342 hours since new. ## Aircraft - Registration: [N221Q](https://openairdocs.org/deregistered/N221Q-2013-09-17), registration cancelled 2013-09-17, S/N TC-804, built 1964 (OpenAirDocs) - Reported make and model: Beech 95-B55 - Registry model: [Beech 95-B55 (T42A)](https://openairdocs.org/model/beech-95-b55-t42a) (registry code 1152706) (OpenAirDocs) - Registry engine: [Continental I0-470 series](https://openairdocs.org/engine/continental-i0-470-series) (registry code 17027, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: TC-804 - Airframe hours: 6344.5 - Engines: Continental IO-470-L 260 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Roba, Inc - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, November 3, 2003, 42.2 hours before - Departed: SGS, South St. Paul, MN - Destination: STP, St. Paul, MN - Airport: STP, St. Paul Downtown Airport, runway 31, 4,115 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 30; injuries: none; commercial, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; last flight review February 10, 2003; seat: right; flight hours: 1,778 total, 100 in this make and model, 1,700 as pilot in command, 65 in the last 90 days, 34 in the last 30 days - Pilot; injuries: none; commercial, private; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 3, valid medical--no waivers/lim.; last flight review August 28, 2003; seat: left ## Weather - Conditions: Visual (VMC), Dusk - Wind: 290° at 16 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 36 °F, dew point 27 °F - Altimeter: 29.93 inHg - Observed at: STP ## 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 20031222033809A](https://openairdocs.org/incident/20031222033809A), Dec 22, 2003: Beech 95B55, St Paul, MN, Substantial damage. (-23) Drag and VMC demo, did 2 landings, on last retraction squeeling sound was heard, several retracton attempts were unsuccessful, gear would not retract,… 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.