# NTSB CHI98LA032: Cessna 421A, N2957Q, Tomahawk, WI, November 7, 1997 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: November 7, 1997, 17:15 local (23:15 UTC) - Place: Tomahawk, WI - Coordinates: 45.470455, -89.720397 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=45.4705&lon=-89.7204&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report February 16, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 10777 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI98LA032 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/10777/pdf - Page: https://openairdocs.org/ntsb/CHI98LA032 ## Probable cause the elevator trim tab bolt backed out, allowing the trim tab to flutter, and destroy the elevator. The factors involved were improper annual inspection by the maintenance personnel, and the inadequate aircraft preflight done by the pilot. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, climb - to cruise - miscellaneous,bolt/nut/fastener/clamp/spring - separation (cause) - maintenance,annual inspection - improper, other maintenance personnel (contributing factor) - flight control,elevator tab - flutter (cause) - aircraft preflight - inadequate, pilot in command (contributing factor) - flight control,elevator - failure,partial ## Analysis On climb out at 11,000 feet at 700 feet per minute rate of climb on autopilot, the pilot heard a loud bang and felt a 'rapid vibration in the control yoke.' The pilot reported pitch trim was not available and said he checked the engines for proper operations. The flight landed without further incident. Examination of the aircraft revealed substantial damage to the right elevator and trim tab. The rear trim tab linkage bolt was missing and there was little damage to the yoke or trim tab bushing. Paint transfer marks were found on the trim tab from the elevator. An undersized cotter pin was found in the forward linkage bolt. ## Factual narrative On November 7, 1997, at 1715 central standard time (cst), a Cessna 421A, N2957Q, operated and owned by an airline transport pilot, sustained an in-flight structural failure of the right horizontal stabilizer trim tab assembly, while on climb out from Tomahawk Airport, Tomahawk, Wisconsin. The pilot reported no injuries. The flight, conducted under 14 CFR Part 91, originated at Tomahawk, Wisconsin, at 1700 cst, with an intended destination of Poplar Grove, Illinois. An IFR flight plan was filed, and visual meteorological conditions prevailed at the time. In the pilot's written statement, he reported that climbing through 11,000 feet at 700 feet per minute rate of climb, on autopilot, he heard a "loud bang..., followed by the disconnect of the a/p [autopilot], a rapid vibration in the control yoke and a pitch down of the aircraft nose." The pilot said he slowed the aircraft down and confirmed that both engines were running properly. When he further slowed the aircraft to 130 miles per hour it "...did not stop or change the vibration." He said pitch trim was not available. The pilot reported his situation to Air Traffic Control and landed without further incident at Merrill Municipal Airport (RRL), Merrill, Wisconsin. Examination of the aircraft by the Federal Aviation Administration revealed extensive damage confined to the right elevator and trim tab. Ribs 1, 2, and 3 of the elevator had substantial separation damage and the elevator spar was severed at the 2nd rib. The examination revealed that the rear trim tab linkage bolt was missing. There was little damage to the yoke or trim tab bushing. The trim tab bushing moved freely. The forward trim tab linkage bolt was found intact and the trim tab linkage was not binding. An undersized cotter pin was found in the forward linkage bolt. The trim tab actuator arm was found to be bent 90 degrees. There was paint transfer to the trim tab from the elevator and transfer damage to the trim tab from the linkage. The trim tab hinge was intact and free moving. ## Aircraft - Registration: [N2957Q](https://openairdocs.org/aircraft/N2957Q), registered now, S/N 421A0057, built 1969 (OpenAirDocs) - Reported make and model: Cessna 421A - Registry model: [Cessna 421A](https://openairdocs.org/model/cessna-421a) (registry code 2076012) (OpenAirDocs) - Registry engine: [Continental GTSIO-520 series](https://openairdocs.org/engine/continental-gtsio-520-series) (registry code 17046, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 421A00057 - Engines: Continental GTISO 520H 375 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Robert Henry Lussow - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 18, 1997 - Departed: WI46 - Destination: C77, POPLAR GROVE, IL - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 54; airline transport, flight engineer, flight instructor; airplane ratings: single-engine sea, multi-engine land, single-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 28,000 total, 300 in this make and model, 26,000 as pilot in command, 40 in the last 90 days, 16 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Dusk - Visibility: 5 statute miles - Lowest ceiling: 4,000 ft overcast - Temperature: 41 °F - Altimeter: 30.00 inHg - Observed at: AUW, 30 nm away ## 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 19971107032639A](https://openairdocs.org/incident/19971107032639A), Nov 7, 1997: Cessna 421A, Tomahawk, WI, Substantial damage. (Tty) acft auto dis on climb out, upon landing the right ele was found severely damaged. Merrill, WI. (.4)on climb out at 11,000 feet at 700 feet per minute… 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.