Mitsubishi MU-2 Marquise

On his first Instrument Landing System (ILS) approach, the pilot initially flew through the localizer course. The pilot then reestablished the airplane on the final approach course, but the airplane’s altitude at the decision height was about 500 feet too high. He executed a missed approach and received radar vectors for another approach. The airplane was flying inbound on the second ILS approach when a witness reported that he saw the airplane about 150 feet above the ground in about a 60-degree nose-low attitude with about an 80-degree right bank angle. The initial ground impact point was about 2,150 feet west of the runway threshold and about 720 feet north (left) of the extended centerline. The cloud tops were about 3,000 feet with light rime or mixed icing. The flap jack screws and flap indicator were found in the 5-degree flap position. The inspection of the airplane revealed no preimpact anomalies to the airframe, engines, or propellers. A radar study performed on the flight indicated that the calibrated airspeed was about 130 knots on the final approach, but subsequently decreased to about 95–100 knots during the 20-second period prior to loss of radar contact. According to the airplane’s flight manual, the wings-level power-off stall speed at the accident aircraft’s weight is about 91 knots. The ILS approach flight profile indicates that 20 degrees of flaps should be used at the glide slope intercept while maintaining 120 knots minimum airspeed. At least 20 degrees of flaps should be maintained until touchdown. The “No Flap” or “5 Degrees Flap Landing” flight profile indicates that the NO FLAP Vref airspeed is 115 knots calibrated airspeed minimum.

According to the pilot, after he took off for a nearby airport he raised the landing gear but did not raise the 20-degree flaps per the “after takeoff” checklist. Shortly thereafter, when the airplane was at an altitude of about 2,400 feet, and in "heavy rain," the pilot noticed that the right engine was losing power. He subsequently feathered the propeller as engine power reduced to 40 percent, but still did not raise the flaps. Weather, recorded shortly before the accident, included scattered clouds at 500 feet, and a broken cloud layer at 1,200 feet, and the pilot advised air traffic control (ATC) that he would fly an ILS (instrument landing system) approach if he could maintain altitude. After maneuvering, and advising ATC that he could not maintain altitude, the pilot descended the airplane to a right base leg where, about 1/4 nautical mile from the runway, it was approximately 300 feet above the terrain. The pilot completed the landing, with the airplane touching down about 6,200 feet down the 8,000-foot runway, heading about 20 degrees to the left. The airplane veered off the left side of the runway and subsequently went through an airport fence. The left engine was running at “high speed” when fire fighters responded to the scene. The right engine propeller was observed in the feathered position at the scene, and after subsequent examinations, the right engine was successfully run in a test cell with no noticeable loss of power. There was no determination as to why the right engine lost power in flight, although rain ingestion is a possibility. Airplane performance calculations indicated that with the landing gear up, a proper single-engine power setting and airspeed, and flaps raised, the airplane should have been able to climb about 650 feet per minute. Even with flaps at 20 degrees, it should have been able to climb at 350 feet per minute. In either case, unless the airplane was not properly configured, there was no reason why it should not have been able to maintain the altitudes needed to position it for a stabilized approach.

Prior to the accident flight, the pilot obtained a preflight weather briefing and filed an instrument flight rules flight plan. The briefer noted no adverse weather conditions along the route. The airplane departed the airport at 0853, and climbed to FL190. The first two hours of the flight was uneventful, and the aircraft was handed off to Jacksonville Air Route Traffic Control Center (ZJX ARTCC) at 1053. The pilot contacted ZJX Crestview sector at 1054:45 with the airplane level at FL190. At 1102, the Crestview controller broadcasted an alert for Significant Meteorological Information (SIGMET) 32E, which pertained to thunderstorms in portions of Florida southwest of the pilot's route. At 1103, the controller cleared to the airplane to descend to 11,000 feet and the pilot again acknowledged. At 1110:21, the pilot was instructed to contact Tyndall Approach. The pilot checked in with the Tyndall RAPCON North Approach controller at 1110:39. The pilot was told to expect a visual approach. Shortly thereafter, the pilot transmitted, "...we're at 11,000, like to get down lower so we can get underneath this stuff." The controller told the pilot to stand by and expect lower [altitude] in 3 miles. About 15 seconds later, the controller cleared to pilot to descend to 6,000 feet, and the pilot acknowledged. At 1112:27, the pilot was instructed to contact Tyndall Approach on another frequency. The airplane's position at that time was just northwest of REBBA intersection. The Panama sector controller cleared the pilot to descend to 3,000 feet at his discretion, and the pilot acknowledged. There was no further contact with the airplane. The controller attempted to advise the pilot that radar contact was lost, but repeated attempts to establish communications and locate the airplane were unsuccessful. A witness, located approximately 1 mile south of the accident site, reported he heard a "loud bang," looked up and observed the airplane in a nose down spiral. The witness reported there were parts separating from the airplane during the descent. The witness stated it was raining and there was lightning and thunder in the area. Local authorities reported that the weather "was raining real good with lightning and the thunderstorm materialized very quickly." The main wreckage came to rest near the edge of a swamp in tree covered and high grassy terrain. The left wing, left engine, and the left wing tip tank were located in a wooded area approximately 0.6 miles northwest of the main wreckage. The left wing separated from the airplane inboard of the left engine and nacelle. Examination of the fracture surfaces indicated that both the front and rear spars failed from "catastrophic static up-bending overstress..." The airplane flew through an intense to extreme weather radar echo containing a thunderstorm. Although the controllers denied that there was any weather displayed ahead of the airplane, recorded radar and display data indicated that moderate to extreme precipitation was depicted on and near the route of flight. During the flight, the pilot was given no real-time information on the weather ahead. The airplane was equipped with a weather radar system and the system provided continuous en route weather information relative to cloud formation, rainfall rate, thunderstorms, icing conditions, and storm detection up to a distance of 240 miles. No anomalies were noted with the airframe and engines.

The pilot had received an outlook briefing during the morning hours before the accident. The briefing included information regarding widely scattered thunderstorms and rain showers along portions of the pilot's planned route of flight. At the time of the accident, a convective weather significant to the safety of all aircraft (convective SIGMET) was in effect for the pilot's route of flight, and the information about the convective SIGMET was broadcast to the pilot by air traffic control (ATC). Several airplanes in the vicinity of the accident airplane were deviating around weather. Conversations between the accident pilot and the ATC controller were consistent with the accident airplane's weather radar functioning, and the possibility that the accident airplane's weather radar was providing more information than the ATC weather radar. Although the pilot initially declined a deviation query by ATC, he later accepted one. Shortly after, the pilot was unable to maintain his assigned altitude of 28,000 feet msl (FL 280), and the airplane impacted terrain consistent with a vertical descent. At the time of the accident, at FL 280, weak to moderate weather radar echoes existed. Very strong to intense weather radar echoes were seen about FL 200. The ATC facility was equipped with NEXRAD derived weather displays. The weather displays had four settings: below FL 240, between FL 240 and FL 330, above FL 330, and from sea level to FL 600. At the time of the accident, the ATC controller's weather display indicated weak to moderate echoes above FL240. Very strong to intense weather radar echoes existed about FL200; however, the ATC controller did not have his weather display set to that altitude as he was not controlling traffic at that altitude. The investigation could not determine if the pilot was aware of the stronger intensity echoes below his altitude, or if the airplane's weather radar was depicting the stronger echoes. Examination of the wreckage did not reveal any preimpact mechanical malfunctions.

Witnesses stated that they observed the twin-engine airplane roll into a steep right bank and enter a spin at a low altitude (less than 700 feet) during the initial climb. The airplane then descended and impacted terrain about 1.5 miles from the end of the departure runway. Some witnesses reported hearing an unusual engine noise just before the airplane began to roll and spin. Day visual meteorological conditions prevailed. Examination of the right engine revealed that the ring gear support of the engine/propeller gearbox had fractured in flight due to high cycle fatigue originating from the corner radii of the high-speed pinion cutout. The reason for the fatigue could not be determined. The ring gear support disengaged from the ring gear due to this failure, resulting in a disconnection in power being transferred from the engine power section to the propeller. In addition to the ability for a pilot to manually feather the propellers, and an automatic feathering feature, the engine (Honeywell TPE-331) design also includes a “Negative Torque Sensing” (NTS) system that would automatically respond to a typical failed engine condition involving a propeller that is driving the coupled engine. Feathering the propeller reduces drag and asymmetric yawing due to the failed engine. All Federal Aviation Administration (FAA) certification evaluations for one-engine inoperative handling qualities for the airplane type were conducted with the NTS system operational. According to the airplane manufacturer, the NTS system was designed to automatically reduce the drag on the affected engine to provide a margin of safety until the pilot is able to shut down the engine with the condition lever. However, if a drive train disconnect occurs at the ring gear support, the NTS system is inoperable, and the propeller can come out of feather on its own, if the disconnect is followed by a pilot action to retard the power lever on the affected engine. In this scenario, once the fuel flow setting is reduced below the point required to run the power section at 100% (takeoff) rpm, the propeller governor would sense an “underspeed” condition and would attempt to increase engine rpm by unloading the propeller, subsequently driving the propeller out of feather toward the low pitch stop. This flat pitch condition would cause an increase in aerodynamic drag on one side of the airplane, and unanticipated airplane control difficulty could result due to the asymmetry.

At 1834 Pacific standard time, the Nav Air Charter Inc. Mitsubishi MU-2B-36 aircraft (registration C-FTWO, serial number 672) took off from Runway 15 at the Terrace Airport for a courier flight to Vancouver, British Columbia. The left engine lost power shortly after take-off. The aircraft descended, with a slight left bank, into trees and crashed about 1600 feet east of the departure end of Runway 15 on a heading of 072° magnetic. The aircraft was destroyed by the impact and a post-crash fire, and the two pilots were fatally injured.

The twin-engine airplane was destroyed when it impacted an earthmoving scraper and terrain in a field about 2.5 miles north of the departure airport in night visual meteorological conditions. Witnesses reported that the pilot had aborted an earlier flight when he returned to the airport and told the mechanic that he had a right engine fire warning light. The discrepancy could not be duplicated during maintenance, and the airplane departed. About 23 minutes after departure, the pilot reported to air traffic control that he needed to return to the airport to have something checked out. The pilot did not report to anyone why he decided to return to the departure airport, and he flew over four airports when he returned to the departure airport. Radar track data indicated that the airplane flew over the departure end of runway 35 at an altitude of about 1,600 feet agl, and made a descending left turn. The airplane's altitude was about 800 feet agl when it crossed the final approach course for runway 35. The airplane continued the descending left turn, but instead of landing on runway 35, the airplane flew a course that paralleled the runway, about 0.8 nm to the right of runway 35. The airplane continued to fly a northerly heading and continued to descend. The radar track data indicated that the airplane's airspeed was decreasing from about 130 kts to about 110 kts during the last one minute and fifty seconds of flight. The last reinforced beacon return indicated that the airplane's altitude was about 200 feet agl, and the airspeed was about 107 kts. The airplane impacted terrain about 0.75 nm from the last radar contact on a 338-degree magnetic heading. A witness reported that the airplane was going slow and was "extremely low." He reported that the airplane disappeared, and then there was an explosion and a fireball that went up about 1,000 feet. Inspection of the airplane revealed that it impacted the earthmover in about a wings level attitude. The landing gear handle was found to be in the landing gear UP position. The inspection of the left engine and propeller revealed damage indicative of engine operation at the time of impact. Inspection of the right engine revealed damage indicative of the engine not operating at the time of impact, consistent with an engine shutdown and a feathered propeller. No pre-existing conditions were found in either engine that would have interfered with normal operation. The inspection of the right engine fire detection loop revealed that the connector had surface contamination. When tested, an intermittent signal was produced which could give a fire alarm indication to the pilot. After the surface contamination was removed, the fire warning detection loop operated normally.

The commercial pilot was executing a precision instrument approach at night in instrument meteorological conditions when the airplane collided with terrain about four miles short of the runway. A review of air traffic control communications and radar data revealed the pilot was vectored onto the final approach course but never got established on the glide slope. Instead, he made a controlled descent below the glide slope as he proceeded toward the airport. When the airplane was five miles from the airport, a tower controller received an aural low altitude alert generated by the Minimum Safe Altitude Warning (MSAW) system. The tower controller immediately notified the pilot of his low altitude, but the airplane collided with terrain within seconds. Examination of the instrument approach system and onboard flight navigation equipment revealed no pre-mishap anomalies. A review of the MSAW adaptation parameters revealed that the tower controller would only have received an aural alarm for aircraft operating within 5 nm of the airport. However, the frequency change from the approach controller to the tower controller occurred when the airplane was about 10.7 miles from the airport, leaving a 5.7 mile segment where both controllers could receive visual alerts, but only the approach controller received an aural alarm. A tower controller does not utilize a radar display as a primary resource for managing air traffic. In 2004, the FAA changed a policy, which eliminated an approach controller's responsibility to inform a tower controller of a low altitude alert if the tower had MSAW capability. The approach controller thought the MSAW alarm parameter was set 10 miles from the airport, and not the 5 miles that existed at the time of the accident. Subsequent investigation revealed, that The FAA had improperly informed controllers to ensure they understood the alarm parameters for control towers in their area of responsibility. This led the approach controller to conclude that the airplane was no longer her responsibility once she handed it over to the tower controller. Plus, the tone of the approach controller's aural MSAW alarm was not sufficient in properly alerting her of the low altitude alert.

Witnesses observed the aircraft perform a rolling takeoff and it was airborne by the crossing runway (1,300 feet down the 6,600 foot runway). The aircraft entered an approximate 40 degree nose high climb rate to about 1,000 feet. The aircraft then entered a steep left hand banking turn. The nose dropped and the aircraft rotated up to about 4 times before colliding with the flat terrain adjacent to the departure end of the runway threshold. On site documentation of the airframe found no evidence of a flight control malfunction. An engine examination and teardown found that the gearbox section of the left engine experienced a high cycle fatigue failure of the high speed pinion journal bearing oil supply tube and subsequent degradation of the high speed pinion journal bearings. This failure resulted in a partial power loss to the left engine. The pilot had recently purchased this aircraft and he had accumulated approximately 11 hours since the purchase. The pilot had stated to personnel at the place where he purchased the aircraft that he had not received, nor did he need recurrent training in this aircraft as he had several thousand hours in the aircraft. Flight logs provided by the family indicated that the pilot had accumulated about 551 hours in a Mitsubishi, however, the last time that the pilot had flown this make and model was 14 years prior to the accident. Logbook entries indicated that only a few hours of flight time had been accumulated in all aircraft during the approximately 2 years prior to the accident. Personnel that flew with the pilot in the make and model aircraft involved in the accident described the pilot as "proficiency lacking." Normal takeoff calculations for the aircraft with the flaps configured to 5 degrees, indicated a ground run of 2,900 feet, with a rotation speed of 106 KCAS, and 125 KCAS for the climb out. A maximum pitch attitude of 13 degrees maximum is indicated. Performance calculations indicated that the aircraft was capable of lifting off where the witnesses observed and climbing to 1,000 feet agl by the end of the runway. To achieve this performance the aircraft would have rotated at approximately 84 KCAS and climbed at an airspeed below Vmc (100 KCAS) and close to power-off stall speed (86 KCAS) with 5 degrees of flaps. The airplane's flight manual indicated that if an engine failure occurs in the takeoff climb and the landing gear is fully retracted, the emergency procedures is to maintain 140 KCAS, flaps to 5 degrees, the failed engine condition lever to EMERGENCY STOP, and failed engine power lever to TAKEOFF. On site documentation found the left side condition lever in the takeoff/land position and the power lever was found half-way between takeoff and flight idle.