Wellsville, MO, USA
N477MD
Piper PA-46-500TP
The pilot, before departure, obtained a weather briefing that indicated there were thunderstorms and areas of heavy precipitation along the route of flight. The pilot told the briefer that the airplane was equipped with onboard radar for weather avoidance. After takeoff, the pilot received two adverse weather advisories from the departure air traffic controller. The pilot acknowledged, requested and was cleared for course deviations to avoid the weather. The pilot was subsequently told to contact an en route traffic control center. The pilot did not request an update on, nor was he advised of, any additional adverse weather after switching over. Avionics data recovered from the wreckage showed the airplane encountered decreasing outside air temperatures (OAT) during the en route climb to a cruise altitude. The OAT decreased below freezing as the airplane climbed through 15,900 feet mean sea level. The primary flight display's (PFD) airspeed data decreased from about 140 knots indicated airspeed (KIAS) to 0 KIAS. During the loss of airspeed, the airplane's recorded climb rate decreased and the airplane entered a left turn. At this point, the en route controller asked the pilot if he had been given a clearance to deviate around weather. The pilot responded, "mike delta we've got problems uh... ." There were no additional communications received from the pilot and radar contact with the airplane was lost shortly thereafter. The recovered PFD data indicated that the airplane exceeded its maximum structural operating speed during a rapid descent. In the descent, the airplane reached a ground speed of 250 knots and vertical loads reaching 5g. The recovered data and witness marks from the right wing indicated the airplane sustained an in-flight breakup after exceeding the airplane's maximum load factor limit. A review of the available weather data indicated that there was an area of extreme precipitation associated with thunderstorms east of the accident site and that the airplane was likely in instrument meteorological conditions at the time of the upset. An on-scene investigation did not reveal any pre-impact anomalies with the airplane and its related systems. Analysis of the recovered PFD and Multi-Function Display (MFD) data indicated that the pilot did not utilize the available pitot tube heat that would have afforded ice protection. Recovered PFD/MFD data, along with a weather analysis, indicated that the airplane was operating in an environment conducive for pitot tube icing. Additionally, recovered data showed airspeeds were recorded during the rapid descent at altitudes lower than the observed freezing level. The before takeoff checklist indicated, "Pitot Heat ... ON."
HISTORY OF FLIGHT On June 28, 2007, about 0815 central daylight time, a Piper PA-46-500TP, N477MD, was destroyed on impact with terrain following an in-flight breakup near Wellsville, Missouri. The personal flight was operating under Title 14, Code of Federal Regulations Part 91. Visual meteorological surface conditions prevailed in the area at the time of the accident. An instrument flight rules (IFR) flight plan was on file and was activated. The pilot and two passengers sustained fatal injuries. The flight originated from the Spirit of St Louis Airport, near Chesterfield, Missouri, about 0750, and was destined for the Buffalo Municipal Airport, near Buffalo, Minnesota. About 0711, a person representing N477MD contacted Kankakee Automated Flight Service Station (AFSS) to file an IFR flight plan and obtain an abbreviated weather update. During the abbreviated weather update, the AFSS briefer advised the pilot that there was heavy rain and thunderstorm activity in Missouri along the aircraft's planned route of flight. The pilot stated that he had onboard radar for weather avoidance. About 0750, N477MD departed SUS, contacted Federal Aviation Administration (FAA) air traffic controller (ATC) on the St. Louis (Gateway) Departure frequency about 0752, and was initially cleared to climb to 4,000 feet. The Gateway controller advised of light to moderate precipitation three miles ahead of the aircraft. The pilot requested a northerly course deviation for weather avoidance, which was approved. About 0753, N477MD was cleared to climb to 10,000 feet. The controller then advised of additional areas of moderate and heavy precipitation ahead of the airplane, gave the pilot information on the location and extent of the weather areas, and suggested a track that would avoid it. The pilot responded that he saw the same areas on his onboard radar and concurred with the controller's assessment. Radar data showed that the airplane flew northwest bound, and then turned toward the west. About 0757, N477MD was instructed to resume the Ozark 3 departure procedure, and the pilot acknowledged. About 0758, the pilot was cleared again to proceed direct to Macon, Missouri (MCM) VHF omnidirectional range distance measuring equipment (VOR/DME), and two minutes later, was instructed to contact Kansas City Center (ZKC). The pilot contacted the ZKC R53 controller at 0800:47, and, after a discussion about the final requested altitude, was cleared to climb and maintain flight level 230. At 0801:42, a position relief briefing occurred and the R53 controller was replaced. The new R53 controller made no transmissions to N477MD, and was replaced by a third controller at 0806:27. The next transmission to N477MD occurred at 0812:26, when the R53 controller asked the pilot if he had been given a clearance to deviate. The flight's radar track showed that the airplane turned to the left. The pilot responded, "mike delta we've got problems uh..." The controller responded by asking the pilot if he was declaring an emergency, and made several other attempts to contact N477MD. The pilot did not respond to any of these calls, and radar contact was lost. None of the three ZKC controllers had given the pilot any weather information during the time he was controlled by ZKC. Ground and aircraft observers located the airplane wreckage about 1040. PERSONNEL INFORMATION The pilot, age 44, held a FAA private pilot certificate with airplane single-engine land and instrument airplane ratings. FAA records showed that the pilot's last medical examination was completed on January 25, 2007, when he was issued a third-class medical certificate with no limitations. On the application for that medical certificate, the pilot reported that he had accumulated 1,000 hours of total flight time. He reported that he had accumulated 100 hours of flight time in the six months prior to that medical certificate application. The pilot obtained flight instruction for the PA-46-500TP from Simcom. A copy of a pilot proficiency certificate indicated that the pilot satisfactorily completed the PA-46-500TP initial course on November 10, 2006. Their training records showed that the pilot requested a flight review and instrument competency as part of the airplane training. The pilot reported to Simcom that he had accumulated 1,000 hours of total flight time, 300 hours of instrument flight time, and 50 hours of turbine aircraft flight time. He further reported that he had accumulated 200 hours of flight time in the last year, 70 hours in the last 90 days, and 25 hours in the last 30 days. AIRCRAFT INFORMATION N477MD, a 2006 Piper PA-46-500TP, Meridian, serial number 4697264, was an all-metal airplane with semimonocoque fuselage and conventional design. The wing was a three-section structure. The center section built-up main spar extended through the lower fuselage and approximately three feet outboard of each main landing gear. This section had two forward spars and a rear spar, which were pin jointed at the fuselage sides. The outboard section of each wing, to within approximately 18 inches of the tip, was a sealed integral fuel cell. Portions of the wing structure were adhesively bonded, and skins were butt jointed and flush riveted for a smooth airfoil surface. An 850-horsepower, Pratt & Whitney Canada PT6A-42A turbo-propeller engine with serial number PCE-RM0284, which was derated to 500-horsepower, powered the airplane. The engine drove a metal, constant speed, electrically deiced, four-bladed Hartzell HC-E4N-3Q propeller. The airplane was equipped with a pressurized cabin, wing flaps, and retractable tricycle landing gear. The airplane had a maximum seating capacity of six occupants, to include two cockpit positions and four cabin positions. The airplane had a certified maximum ramp weight of 5,134 lbs. The airplane was maintained under a progressive inspection program. The program cycle consists of two 100-hour events, which provides for a complete aircraft inspection in 200 aircraft flying hours. The complete inspection cycle, Events 1 and 2, must be completed within 12 calendar months. Event 2 was completed on June 20, 2007, and the airplane was returned to service. The airplane Hobbs meter was recorded as 201.7 hours at the time of that event inspection. The airplane was equipped with dual Avidyne Flightmax Entegra EXP5000 Primary Flight Displays (PFD) and an Entegra EX5000 Multi-Function Display (MFD). Each PFD starts up once power is applied. The PFD was designed to display indicated air data to include indicated airspeed, altitude, vertical speed, outside air temperature, true airspeed, and ground speed. The PFD indications included attitude data, navigation data, and flight director command bars. The PFD could display engine parameters to include engine torque, inter-turbine temperature, fuel flow, fuel quantity, and engine start parameters. Each PFD contained two flash memory devices mounted on a riser card. The flash memory stored information that the PFD unit used to generate the various primary flight data displays. Additionally, the PFD had a data logging function, which is used by the manufacturer for maintenance and diagnostics. The PFD sampled and stored several data streams in a sequential fashion; when the recording limit of the PFD was reached, the oldest record was dropped and a new record was added. Data from the Air Data and Attitude Heading Reference System (ADAHRS) such as pitch, roll, heading, and accelerations were recorded at a rate of 5 times per second (Hz). Air data information such as pressure altitude, indicated airspeed, and vertical speed were recorded at 1 Hz. GPS and navigation display and setting data were recorded at a rate of .25 Hz, and information about pilot settings of heading, altitude, and vertical speed references were recorded when changes are made. The MFD display indicated navigation data to include a moving map presentation. The MFD displayed engine and electrical system parameters. The MFD displayed information from the X-band on-board radar that was designed for weather location and analysis and for ground mapping. The radar system was designed to detect storms along the flight path and gave pilots a visual colored indication of storm intensity. Intensity was displayed in five color levels with black representing weak or no returns and green, yellow, red, and magenta indicating progressively stronger returns. The MFD displayed detected electrical discharge information from the Stormscope WX-500 unit. The MFD unit contained a compact flash memory card located in a slot on the side of the unit. This memory card contained all of the software that the MFD needed to operate. Like the PFD, the MFD also had a data logging function, which stored periodic information such as engine parameters and flight track data. Specifically, the MFD recorded GPS position, engine performance data (such as torque, interstage turbine temperature, fuel flow, outside air temperature) and some electrical bus conditions. This data was also stored on the unit's compact flash memory card. The MFD generated new data files for each power-on cycle. Similar to the PFD, the oldest file was dropped and replaced by a new file once the storage limit has been reached. MFD data was sampled every six seconds, and was recorded to its memory card once every minute. If an interruption of power occurred during the minute between MFD memory write cycles, data sampled during that portion of a minute were not recorded. The cockpit's right side instrument panel contained a placard about eye level. The placard stated, "STORMSCOPE NOT TO BE USED FOR THUNDERSTORM AREA PENETRATION." A copy of a letter regarding the pilot's revocation of acceptance of the airplane purchase was reviewed. The letter referenced maintenance issues to include PFD and MFD issues. Airplane maintenance logbook entries showed that the indicated issues were repaired prior to the accident. The airplane's pilot operating handbook (POH) limitation section listed 127 knots indicated airspeed (KIAS) as the airplane's maximum operating maneuvering speed (Vo). The limitation associated with Vo stated, "Do not make full or abrupt control movements above this speed." The POH listed 188 KIAS as the airplane's maximum operating speed (Vmo). The limitation associated with Vmo stated, "Do not exceed this speed in any operation." The airplane's flight load factor limit was 3.7 g with flaps up. The POH normal procedures section, in part, stated: Turbulent Air Operation In keeping with good operating practice, it is recommended that when turbulent air is encountered or expected, the airspeed be reduced to maneuvering speed to reduce the structural loads caused by gusts and to allow for inadvertent speed build-ups which may occur as a result of the turbulence or of distractions caused by the conditions. The POH emergency procedures section, in part, stated, "AIRSPEEDS FOR EMERGRNCY OPERATIONS ... OPERATING MANEUVERING SPEED 127 KIAS. The pilot's instrument panel contained a placard about eye level. That placard read, "Vo 127 KIAS." The pilot's and copilot's pitot tube provided ram air inputs to their respective PFD's ADAHRS. The POH, in part, stated: Pitot pressure for the airspeed indicators is sensed by heated pitot heads installed on the bottom of the left and right wings and is carried through lines within the wing and fuselage to the two ADAHRS units on the PFDs. Static pressure for the two ADAHRS units and standby altimeter and airspeed indicators is sensed by static source ports on the underside of the fuselage. ... An alternate static source control valve is located below the instrument panel to the left of the pilot. For normal operation, the lever remains down. To select alternate static source, place the lever in the up position. When the alternate static source is selected the airspeed and altimeter and vertical speed indicator are vented to alternate static ports on the aft sides of the fuselage. During alternate static source operation, these instruments may give slightly different readings. ... If one or more of the pitot static instruments malfunction, the system should be checked for dirt, leaks or moisture. The holes in the sensors for pitot and static pressure must be fully open and free from blockage. Blocked sensor holes will give erratic or zero readings on the instruments. Both the pitot and static can be drained through separate drain valves located on both the right and left lower side panel next to the crew seats. Three drains exist on the pilot side. The forward valve is the pilots PFD primary static drain. The middle drain is the alternate static drain. The aft drain is the left hand pitot drain. Two drains exist on the copilot side. The forward valve is the copilot's PFD primary static drain. The aft drain is the right hand pitot drain. The heated pitot heads, which alleviate problems with icing and heavy rain, are standard equipment. The switch for pitot heat is located on the right overhead switch panel. Static source ports have been demonstrated to be non-icing; however, in the event that icing does occur, selecting the alternate static source will alleviate the problem. According to the POH, the airplane's annunciator panel was equipped with an amber caution light that displayed "PITOT HEAT OFF" which "Indicates the pitot heat has not been selected ON." The annunciator also contained two red warning lights that displayed L[eft] PITOT HEAT and R[ight] PITOT HEAT which indicates that the respective side "pitot heat has failed." The "BEFORE TAKEOFF" checklist in the POH stated, "Pitot Heat ... ON." According to a Piper Aircraft representative, their data for similarly equipped Meridians showed an increase of approximately 13 amperes when the pitot heat is turned on. The pitot heat system is designed to cycle itself on and off at a 30-second rate while the airplane is on the ground with the pitot heat switch selected on. While in-flight and the pitot heat selected on, the pitot heat is on continually and it does not cycle. The airplane was equipped with backup flight instruments including a barometric altimeter, an airspeed indicator, and a direct current powered electromechanical attitude indicator. The attitude indicator was powered from an emergency battery and was designed to operate for 45 minutes after the loss of the airplane electrical system. The backup airspeed indicator was connected to the pilot's PFD pitot tube source. METEOROLOGICAL INFORMATION A National Transportation Safety Board (NTSB) Senior Meteorologist prepared a Meteorological factual report. The report indicated that the 0819 radar summary chart depicted a band of echoes across central Missouri which were characterized as heavy and associated with rain showers with cell movement to the east at 22 knots and echo tops to 33,000 feet above mean sea level (MSL). An area of "extreme" intensity echoes associated with thunderstorms was depicted over eastern Missouri, which was east of the accident site. National Weather Service Weather Surveillance Radar-1988, Doppler (WSR-88D) reflectivity images were reviewed. The WSR-88D images depicted radar returns of 30 to 45 dBZ consistent with “moderate to heavy” intensity echoes along the flight track and the upset location. Geostationary Operations Environmental Satellite number 12 (GOES-12) visible and infrared imagery data surrounding the time of the accident was obtained. The GOES-12 infrared imagery depicted an enhanced band of clouds along and ahead of the front, which extended over the accident site. The GOES-12 visible image depicted an area of enhanced clouds over central and northern Missouri. The clouds identified north of St. Louis and in the vicinity of the accident site were consistent with cumulus clouds with significant vertical development. The clouds could be classified as cumulus congestus to nimbostratus type clouds, with cumulonimbus type clouds developing north of the St. Louis area. The cloud types depicted over the accident airplane's track increased the likelihood that the flight was in instrument meteorological conditions (
The pilot's failure to activate the pitot heat as per the checklist, resulting in erroneous airspeed information due to pitot tube icing, and his subsequent failure to maintain aircraft control. Contributing to the accident was the pilot's continued flight in an area of known adverse weather.
Source: NTSB Aviation Accident Database
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