# NTSB CHI96IA066: Fairchild SA227-AC, N159MC, Bemidji, MN, December 28, 1995 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: December 28, 1995, 17:48 local (23:48 UTC) - Place: Bemidji, MN - Coordinates: 47.479991, -94.869613 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=47.4800&lon=-94.8696&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 16 uninjured - Status: Completed, report May 9, 1996 - Report: Approved by Office Director - NTSB case key (mKey): 10115 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI96IA066 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/10115/pdf - Page: https://openairdocs.org/ntsb/CHI96IA066 ## Probable cause inadequate maintenance installation and inspection of the elevator flight control system which led to restricted flight control elevator movement due to a loose bolt. ## 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 - final approach - flt control syst,elevator control - loose part/bolt/nut/clamp/etc (cause) - maintenance,installation - improper, company maintenance personnel (cause) - maintenance,inspection - inadequate, company maintenance personnel (cause) - flight control,elevator - movement restricted - Hard landing, landing - flare/touchdown ## Analysis On short final, the crew noticed that the airplane had restricted up-elevator movement. They initiated a go-around and used power to control pitch for landing. Excessive descent rate and airspeed resulted in a hard landing. Postincident examination revealed a loose upper elevator stop bolt that had contacted a stringer, preventing further movement of the control column. Sixteen flights earlier, maintenance records show extensive work done to the elevator quadrant. During this work, hardware was 'loosely installed' on the quadrant so as to not be lost. The position of a nut run down on the bolt is close to the appearance of a nut properly torqued. ## Factual narrative On December 28, 1995, at 1748 central standard time (CST), a Fairchild SA227-AC, N159MC, operated by Mesaba Airlines, of Minneapolis, Minnesota, received no damage after the captain reported that the airplane had restricted elevator travel on landing at Bemidji County Airport, Bemidji, Minnesota. There were no injuries to the two crew members, or 14 passengers aboard the airplane. There was no emergency evacuation. The flight was a domestic passenger flight, operating under 14 CFR Part 135, from Minneapolis to Bemidji, Minnesota. Visual meteorological conditions prevailed at the time, and an IFR flight plan was filed. According to the pilot's written statement, during a normal descent on short final (100 to 200 feet above ground) in landing configuration, the crew reported that the airplane pitched down excessively and the elevator could not be moved to the full up position. The crew initiated a go-around and used power to control pitch for landing. The landing was hard and flat. Sixteen flights before this incident, the tail section had maintenance conducted on it according to Mesaba's maintenance records. The Federal Aviation Administration Principal Maintenance Inspector (PMI) stated that Mesaba records show maintenance performed on N159MC in the area of the elevator quadrant. During the maintenance, a mechanic following maintenance manual procedures, removed the upper elevator bolt and related hardware. A mechanic who performed maintenance on the airplane stated that with the quadrant removed and on a bench, another mechanic loosely installed the hardware back on to the quadrant, so the hardware would not be lost. "Loosely installed" as stated by the mechanic refers to the bolt and related hardware installed, with the self locking nut tightened manually and not properly torqued. The self locking feature of the nut was deteriorated. The nut that was removed from N159MC could be run down on the bolt to a point where one thread extended beyond the nut. This position on the nut is close to the appearance of a nut installed with the proper torque. The FAA Inspector stated that in comparison to a new nut it could only be run down a few turns on the bolt. Mesaba's inspector did not notice the improper installation. The post-maintenance investigation found a worked out upper elevator stop bolt in the elevator quadrant prevented elevator movement from about neutral to full up position. The bolt worked out about two inches. Upon movement of the control column to the full up position, the worked out bolt, moving upward with the elevator control quadrant, contacted the underside of a stringer (the first stringer just above the related access panel on the right side of the vertical stabilizer). This contact prevented further movement of the elevator in the up direction. The bolt appeared to be bent from this contact and force exerted by the crew when pulling the control column back. ## Aircraft - Registration: [N159MC](https://openairdocs.org/aircraft/N159MC), registered now, S/N AC-728B (OpenAirDocs) - Reported make and model: Fairchild SA227-AC - Registry model: [Fairchild SA227-AC](https://openairdocs.org/model/fairchild-sa227-ac) (registry code 3377509) (OpenAirDocs) - Registry engine: [AiResearch TPE331 series](https://openairdocs.org/engine/airesearch-tpe331-series) (registry code 01514, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: AC-728B - Airframe hours: 10953 - Engines: Garrett 331 1100 horsepower turbo prop - Damage: No damage - Flight: Part 135 - Operator: Mesaba Airlines, Inc., doing business as Mesaba Airlines - Registered owner: Ccd Air Twenty One, Inc. - Airworthiness certificate: Standard, Normal - Last inspection: Continuous airworthiness, December 9, 1995, 104 hours before - Departed: MSP, MINNEAPOLIS, MN - Flight plan: IFR - Airport: BJI, Bemidji County, runway 13, 6,598 × 150 ft ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 36; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: left; flight hours: 5,600 total, 3,400 in this make and model, 2,200 as pilot in command, 116 in the last 90 days, 60 in the last 30 days, 8 in the last 24 hours ## Weather - Conditions: Visual (VMC), Dusk - Wind: 210° at 9 knots - Visibility: 10 statute miles - Lowest ceiling: 12,000 ft broken - Temperature: 19 °F, dew point 14 °F - Observed at: BJI ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 19951228045239I](https://openairdocs.org/incident/19951228045239I), Dec 28, 1995: Swrngn SA227AC, Bemidji, MN. Narrative: on December 26, 1995 mesaba records show extensive maintenance on fairchild SA-227 aircraft N159MC in the area of the elevator quadrant. During the… 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.