# NTSB MIA01FA206: Mitsubishi MU-2B-35, N1VY, Hilton Head, SC, August 1, 2001 - Type: NTSB accident investigation - Classification: Accident · Fatal · Field investigation · Final report - Date: August 1, 2001, 07:51 local (11:51 UTC) - Place: Hilton Head, SC - Coordinates: 32.164722, -80.733612 - Nearby events: https://openairdocs.org/map.md?lat=32.1647&lon=-80.7336&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: Fatal - Injuries: 1 fatal - Status: Completed, report December 30, 2003 - Report: Approved by Office Director - Parties: Mitsubishi Heavy Industries America, Inc., Bankair Inc., FAA FSDO, Honeywell Corporation - ADs cited in the narratives: [AD 88-23-01](https://openairdocs.org/ad/88-23-01) (OpenAirDocs) - NTSB case key (mKey): 52945 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA01FA206 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/52945/pdf - Page: https://openairdocs.org/ntsb/MIA01FA206 ## Probable cause Improper maintenance/installation and and inadequate inspection of the airplane's flap torque tube joints during routine maintenance by company maintenance personnel, which resulted in the right flap torque tube assembly coupler becoming detached and the flaps developing asymmetrical lift when extended, which resulted in an uncontrolled roll, a descent, and an impact with a tree during approach to land. ## 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 - maintenance,compliance with ad - attempted, company maintenance personnel - maintenance,installation - improper, company maintenance personnel (cause) - maintenance,inspection - inadequate, company maintenance personnel (cause) - flt control syst,wing flap control cable/rod - loose part/bolt/nut/clamp/etc (cause) - Loss of control - in flight, approach - vfr pattern - final approach - aircraft control - not possible, pilot in command - In flight collision with object, descent - uncontrolled - object - tree(s) - In flight collision with terrain/water, descent - uncontrolled - terrain condition - ground ## Analysis The airplane was on final approach to land at Hilton Head Airport, when according to witnesses, it suddenly rolled to the right, and descended, initially impacting trees at about the 70-foot level, and then impacting the ground. A fire then ensued upon ground impact, and the debris field spanned about 370 feet along an azimuth of about 082 degrees. Examination of the airplane wreckage revealed that left wing flap actuator and jack nut measurements were consistent with the wing flaps being extended to 40 degrees, and on the right wing the flap jack nut and actuator measurements were consistent with the right flap being extended to about a 20-degrees. In addition, the right flap torque tube assembly between the flap motor and the flap stop assembly had disconnected, and the flap torque tube assembly's female coupler which attaches to the male spline end of the flap motor and flap stop assembly was found with a cotter pin installed through the female coupler of the flap stop assembly. The cotter pin, had not been placed through the spline and the coupler consistent with normal installation as per Mitsubishi's maintenance manual, or as specified in Airworthiness Directive 88-23-01. Instead, the cotter pin had missed the male spline on the flap motor. In addition, the flap coupler on the opposite side of the flap motor was found to also found to not have a cotter pin installed. Company maintenance records showed that on April 3, 2001, about 87 flight hours before the accident, the airplane was inspected per Airworthiness Directive (AD) 88-23-01, which required the disassembly, inspection, and reassembly of the flap torque tube joints. In addition, on July 9, 2001, the airplane was given a phase 1 inspection, and Bankair records showed that a company authorized maintenance person performed the applicable maintenance items, and certified the airplane for return to service. ## Factual narrative HISTORY OF FLIGHT On August 1, 2001, about 0751 eastern daylight time, a Mitsubishi, MU-2B-35, N1VY, registered to MU-2 LLC, and operated by Bankair Inc., as a Title 14 CFR part 91 positioning flight, crashed in Hilton Head, South Carolina. Visual meteorological conditions prevailed, and an instrument flight rules flight plan had been filed. The commercial-rated pilot, sole occupant of the aircraft, received fatal injuries, and the aircraft was destroyed. The flight originated from Savannah, Georgia, the same day, about 0741. The chief pilot of Bankair Inc. stated that the pilot had just flown the aircraft from Columbia, South Carolina, to Savannah, Georgia, as Bankair flight 170, a Title 14 CFR part 135 flight, and had dropped off his cargo. The chief pilot further stated that the pilot was positioning the aircraft to Hilton Head to pick up additional cargo, when the accident occurred. An FAA Savannah Air Traffic Control Tower North Radar Controller said that the pilot had been on an IFR flight plan from Savannah, to Hilton Head, had reported the airport in sight, and had been given approval to make a frequency change, and told to squawk 1200. According to the controller, at 0750, he noticed on radar that N1VY had initiated a gradual descent from 2,000 feet to 1,000 feet, and at 0751, the altitude rose slightly to 1,300 feet and then N1VY disappeared from the radar screen. According to a person at the Hilton Head Airport who was monitoring the unicom frequency, the pilot of the accident airplane called on the unicom frequency, and asked for a traffic advisory, and he had responded to the pilot saying that traffic was landing and departing from runway 3. The witness further stated that the pilot responded saying, "thank you, traffic landing and departing runway 3", and that was the only communication he had with the pilot. Witnesses reported seeing the aircraft in a right wing down, nose-low flight attitude as it initially impacted trees, and then impacted the ground on a golf course in the Leamington section of the Palmetto Dunes Plantation. Upon impact, a postcrash fire ensued, and the aircraft was destroyed. PERSONNEL INFORMATION Information obtained from Bankair Inc., showed that the pilot held an FAA commercial pilot certificate, with airplane single and multiengine land and instrument airplane ratings, issued by the FAA on January 11, 1998. The information also showed that he held a commercial helicopter certificate with an instrument rotorcraft rating, as well as a FAA Airframe and Powerplant mechanic's license that had been issued March 21, 1996. The pilot held an FAA second class medical certificate issued on January 22, 2001, with the stated limitation that "holder shall wear correcting lenses while exercising the privileges of this certificate." Bankair records showed that after initially working as a mechanic for Bankair, commencing on July 16, 1996, on March 26, 1998, the pilot became a Bankair pilot. At the time of the accident, he had accumulated a total of about 4,100 flight hours, with about 500 flight hours in the same type airplane as the accident airplane, and about 114 flight hours during the past 90 days, of which about 77 was in the Mitsubishi MU-2. He also had received recurrent training on the MU-2 at Howell Enterprises in November 2000, and had last been given a flight competency check on April 18, 2001. AIRCRAFT INFORMATION N1VY was a 1972 Mitsubishi MU2B-35, serial number 567. It was equipped with two 665-shaft horsepower Garrett TPE-331-6-252M turbo-propeller engines, and the serial number of the No. 1 engine, was P20543C, and that of the No. 2 engine was P20432C. N1VY was also equipped with two Hartzell constant speed, controllable pitch, reversible, full automatic and manual feathering 3-bladed metal propellers. The left propeller hub's serial number was BVA6652. the serial number of the right hub was BVA6643. The airplane was being maintained under an FAA Approved Aircraft Inspection Program, and according to maintenance records obtained from Bankair, on April 3, 2001, about 87 flight hours before the accident, N1VY was inspected per Airworthiness Directive (AD) 88-23-01, which required the dissassembly, inspection, and reassembly of the flap torque tube joints. The airplane received an inspection on July 9, 2001, and at the time of that Phase 1 inspection, it had accumulated a total time of 11,594.1 hours. The No. 1 engine had accumulated 2010 cycles, a time of 1946.7 hours since overhaul, and a total time on the engine of 6735.6. The No. 2 engine had accumulated 2010 cycles, 1946.7 hours since overhaul, and a total of 7919.8 hours. At the time of the accident the airplane had accumulated a total of 11,612.7 hours. METEOROLOGICAL INFORMATION Visual meteorological conditions prevailed at the time of the accident. The Savannah International Airport 0750 surface weather observation was few clouds at 2,500 feet, visibility 10 statute miles, winds from 050 degrees at 8 knots, temperature 23 degrees C, dewpoint temperature 20 degrees C, altimeter setting 30.24 inHg. Savannah is located about 27 nautical miles west of the accident site. WRECKAGE AND IMPACT INFORMATION N1VY was on final approach for landing at Hilton Head Airport, Hilton Head, South Carolina when it impacted trees and the ground the ground on the Palmetto Dunes Plantation golf course in the Leamington Plantation complex. The airplane came to rest in the in the vicinity of 54 Leamington Court, about 3.5 miles southwest of the Hilton Head Airport in position 32 degrees, 09 minutes 53.5 seconds N, 080 degrees, 44 minutes 15.1 seconds west. The main wreckage was located on a small rise in a predominantly level portion of the fairway. The airplane had initially impacted a tree at about the 70-foot level, and then impacted the ground, with the main wreckage coming to rest on the knoll at the edge of the tree-line, just prior to the fairway. The debris field with the majority of the airplane parts, spanned a distance of about 110 feet from the initial impact point with the tree, to the area where the main wreckage lay at the edge of the fairway. The debris field then continued along the same general direction, but with fewer airplane parts being present, for about an additional 160 feet, near the far end of the fairway. The azimuth from the initial impact point to the main wreckage along the centerline of the debris field was 082 degrees, and the descent angle, as indicated by impact signature on trees, with respect to the initial ground impact point, was about 40 degrees. The accident airplane sustained extensive fire and impact damage, consistent with a high energy, high velocity impact. Postcrash examination of the airplane revealed that control surfaces, necessary to sustain flight, were in the vicinity of the main wreckage/debris field. The cabin/cockpit lay on the right side, and it had opened up during the impact sequence. In addition, the cabin/cockpit had been consumed by fire with instruments and gages having been destroyed. Flight control continuity was established from the areas where the control surfaces are normally attached, to fracture zones in the main fuselage. All separations of the airplane's control cabling were consistent with overstress. The empennage had separated from the remainder of the fuselage, but the rudder remained attached to the empennage via the rudder torque tube. The rudder trim actuator measured 7 9/16 inches, which equates to 21 degrees nose right trim, and the trim indication at the pedestel showed neutral. The right elevator trim tab actuator was extended 3 1/4 inches, which was beyond normal travel, and the left elevator trim tab actuator measured 1 3/8 inches, which equates to 18 degrees nose up trim. The left wing separated from the main fuselage, and it sustained impact as well as fire damage. The left wing spoiler was fully retracted. Th ## Aircraft - Registration: [N1VY](https://openairdocs.org/deregistered/N1VY-2002-01-23), registration cancelled 2002-01-23, S/N 567, built 1972 (OpenAirDocs) - Reported make and model: Mitsubishi MU-2B-35 - Registry model: [Mitsubishi MU-2B-35](https://openairdocs.org/model/mitsubishi-mu-2b-35) (registry code 5780411) (OpenAirDocs) - Registry engine: [AiResearch TPE331-5&6SER](https://openairdocs.org/engine/airesearch-tpe331-5-6ser) (registry code 01515, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 567 - Airframe hours: 11612.7 - Engines: Garrett TPE331-6-252M 665 horsepower turbo prop; Garrett TPE331-6-252M 665 horsepower turbo prop - Damage: Destroyed - Fire: On-Ground - Flight: Positioning, Part 91 - Registered owner: Bankair Inc - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, July 9, 2001, 21.3 hours before - Departed: SAV, Savannah, GA - Destination: HXD, Hilton Head, SC - Flight plan: IFR - Airport: HXD, Hilton Head, runway 3, 4,300 × 75 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; injuries: fatal; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: helicopter; medical: class 2, valid medical--w/ waivers/lim; last flight review March 2, 2001; seat: left; toxicology performed; flight hours: 4,184 total, 483 in this make and model, 114 in the last 90 days, 46 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 40° at 9 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 68 °F - Altimeter: 30.23 inHg - Observed at: SAV, 26 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 20010801023399A](https://openairdocs.org/incident/20010801023399A), Aug 1, 2001: Mtsbsi MU2B35, Hiltonhead, SC, No damage, 1 fatal. (-23) This investigation disclosed that the center wing flap torque tube assembly was installed improperly which resulted in a split flap configuration that… 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.