Jacksonville, MD, USA
N324ST
PIPER PA-32R-301
The instrument-rated private pilot obtained a weather briefing and filed an instrument flight plan for a personal flight that would occur the following morning to attend a stock car race. On the morning of the accident, the pilot contacted air traffic control (ATC) to obtain an instrument clearance. The pilot was given a clearance and was told that it would be void in 10 minutes. Two minutes prior to the expiration of the ATC void time, the pilot departed. Recorded non-volatile memory (NVM) data from the electronic cockpit flight display system were downloaded and analyzed by investigators, and these data greatly aided in the investigation. Analysis of the data indicated that, while climbing in instrument conditions, and most likely using the autopilot, the pilot attempted to increase the airplane’s climb rate by using the vertical speed bug on the electronic (glass) Primary Flight Display (PFD) in the cockpit. However, the NVM data revealed that the PFD had failed to “align”, and was not fully functional. As a result of the PFD not being aligned, the bug settings (altitude and vertical speed) were suppressed, and not transmitted to the autopilot computer. Therefore, when the pilot attempted to increase the airplane’s vertical speed using the PFDs vertical speed bug, the changes were not transmitted to the autopilot computer and the autopilot did not command an increase to the rate of climb. Subsequently, the rate of climb momentarily increased twice, most likely due to pilot control inputs via the control wheel. (A review of the PFD Pilot's Guide revealed that it does not provide information to the pilot regarding the suppression of the bug settings when the PFD is not aligned.). Soon after the last vertical speed bug change, the airplane’s vertical speed began to fluctuate (and oscillate between climbing and descending) significantly. These fluctuations continued for the remainder of the flight (about 9 minutes). During this period, the airplane completed three left-hand orbits at varying altitudes. The pilot then reported an “autopilot problem” to ATC, and he requested a clearance to divert to a nearby airport. The airplane’s course deviated again to the left, after which the pilot again reported a problem with the autopilot. The airplane continued to fly for another 4 minutes as the vertical speed continued to oscillate. The airplane’s ground track remained erratic and was not consistent with a course toward the diversion airport. The airplane entered an uncontrolled descent, impacted terrain, and was destroyed. Examination of the wreckage revealed that the pitch trim jackscrew was in the full nose-down position. No preimpact malfunctions of the autopilot or flight control systems were discovered. The nose-down trim condition likely resulted from the pilot pulling on the control wheel with the autopilot engaged which would have resulted in the trim running nose down. Exams of the airplane’s other systems, structure and engine did not reveal any evidence of preimpact malfunctions or failures. Risk factors for spatial disorientation were present at the time of the accident, including IMC and maneuvering flight. Analysis of the airplane’s flight path during the accident flight, and the pilot’s communications with ATC, indicates that the pilot became spatially disoriented while attempting to maneuver with reference to a degraded PFD. The pilot was instrument current and qualified and he had accumulated about 291 hours operating the electronic flight display system. He had received formal training in two models of airplanes equipped with the same flight display system, and also experienced a failure of the display system on a previous airplane. Thus, the pilot was likely familiarized with the functionality of the PFD. Analysis of the NVM data from the PFD revealed that the PFD had not aligned during its “power cycle” of the accident flight, nor had it aligned on the previous power cycle that occurred on the day of the accident. The recorded data do not explicitly indicate the reason for the failure to align on either cycle; however, the previous power cycle was 333 seconds in duration, and the data indicate that the airplane was moving (taxing) at that time. Movement during this initial, critical alignment phase hinders the system’s ability to align as it attempts to calculate the steady state bias of its rate sensors, and the PFD screen will display a message that states: “INITIAL AHRS ALIGNMENT / REMAIN STATIONARY / OK TO TAXI in xx SECONDS”. After the 333-second power cycle, the system was shut down and restarted for the accident flight. No movement was recorded during the critical alignment period of this power cycle, although the airplane did taxi during the “OK TO TAXI” period of the alignment sequence. The investigation could not conclusively determine why the PFD would not align; however, the airplane departed 375 seconds after the PFD power cycle start-up, which may not have been sufficient time for the system to align. Typical time to align while remaining stationary is 166 seconds. The time to align when taxiing during the “OK TO TAXI” period varies considerably, based on the taxi motion and duration. During a previous taxi event that was similar to the one on the day of accident, the time to align was 416 seconds. According to the flight display manufacturer, the failed alignment in both power cycles would have resulted in red X’s being displayed on the PFD. Based on the information recovered from the accident unit, it is likely that red X’s were displayed at the time of the takeoff. Regardless, the airplane was equipped with traditional standby flight instruments (specifically an attitude indicator, an altimeter, an airspeed indicator, a magnetic compass), and dual global positioning systems, which should have provided sufficient information for the pilot to have maintained situational awareness to allow for continued safe flight after failure of the PFD. The investigation revealed a history of numerous failures of multiple types that affect the flight display system’s reliability. Additionally, examination of the accident airplane’s magnetometer also revealed evidence of fretting corrosion in flight critical components which could result in further malfunctions and failures. However, the investigation did not confirm whether any malfunction or failure of the electronic flight display system was present at the time of the accident takeoff, other than the PFD’s failure to align prior to departure.
HISTORY OF FLIGHT On March 24, 2007, about 0920 eastern daylight time, a Piper PA-32R-301, N324ST, was destroyed when it impacted terrain following a loss of control while maneuvering near Jacksonville, Maryland. The certificated private pilot and two passengers were fatally injured. Instrument meteorological conditions (IMC) prevailed for the flight that departed Harford County Airport (0W3), Churchville, Maryland, about 0906, destined for Virginia Highlands Airport (VJI), Abingdon, Virginia. An instrument flight rules (IFR) flight plan was filed for the personal flight conducted under 14 Code of Federal Regulations (CFR) Part 91. According to transcripts provided by the Federal Aviation Administration (FAA), the accident pilot contacted the Williamsport Automated Flight Service Station via telephone on the day prior to the accident to obtain a weather briefing and to file an IFR flight plan. During the briefing, the pilot indicated that he was going to fly to VJI so that he could attend a NASCAR race in Bristol, Tennessee. The next morning, the pilot contacted Potomac Terminal Radar Approach Control (TRACON) to obtain his IFR clearance. At 0858, the pilot was given a clearance and was told that the clearance would be void at 0908 (10 minutes). The pilot acknowledged. Eight minutes later the pilot departed and contacted Potomac TRACON shortly after departure. The airplane’s Avidyne Entegra flight deck instrumentation was capable of recording some flight data and other parameters. Safety Board investigators downloaded these data, and compared them to air traffic control (ATC) recorded radar and voice data provided by the FAA. The flight deck instrumentation data revealed that the Primary Flight Display's (PFD) Attitude Heading Reference System (AHRS) had failed to align twice on the day of the accident; once on the electrical power cycle preceding the accident flight, and again when the PFD was started up for the accident flight. According to Avidyne, if the PFD is not aligned, then heading data, Horizontal Situation Indicator (HSI) navigation data, and attitude data are removed from the display and replaced with Red “Xs". The PFD also cannot be used to control the autopilot computer, limiting the available functionality of the autopilot. The PFD would still however, display altitude, airspeed, and vertical speed. According to the recorded data, prior to takeoff, the vertical speed “bug” on the PFD was set at 750 feet per minute (fpm). The airplane then took off, maneuvered to a westerly heading on track to the Westminster VOR, and at 09:06:37 established an indicated climb rate of about 450-500 fpm. At 09:07:11, the airplane was at an altitude of about 1,440 feet msl and ATC instructed the pilot to climb and maintain 8,000 feet. The PFD altitude bug changed from 5,000 to 8,000 feet. At 09:08:24, the airplane was at an altitude of about 2,000 feet msl and ATC asked “verify you are climbing”. The pilot responded with “say again please.” ATC replied, “climb and maintain eight thousand,” which the pilot acknowledged. At 09:08:37, the data indicated that the PFD’s vertical speed bug setting changed from 750 fpm to 950 fpm. About 09:09:24, the setting increased to 1,050 fpm. At the same time, the pitch attitude reversed its downward trend to an upward trend. About 16 seconds later, a vertical speed was established at about 1,100-1,200 fpm, which lasted for approximately 43 seconds. During this 43-second period, the pitch attitude continually increased at a relatively constant rate, and airspeed decreased at relatively constant rate from about 115 knots to about 94 knots. Also during this 43-second period, the vertical speed bug setting reduced twice; first to 850 fpm and once again to 750 fpm. However, the vertical speed remained at 1,100-1,200 fpm. After this period, the vertical speed began to fluctuate, at times reaching peaks of 5,000 fpm down, and 7,500 fpm up. The fluctuation continued until the end of the recording. Altitude, pitch attitude, airspeed, and vertical acceleration also continued to fluctuate until the end of the recording, with trends consistent with the vertical speed trend. Twenty seconds after the vertical speed fluctuations began, at about 09:10:53, the airplane began the first of three 360-degree turns to the left. As the turn began, the trend of roll attitude was initially to the left followed by a reversal and brief trend to the right before reversing again and remaining left wing down (though oscillating in value) for the duration of the 3 “orbit” turns to the left. During these turns, the vertical speed, airspeed, and pitch and roll attitudes continued to fluctuate. About halfway through the set of turns, at 09:12:15, the pilot transmitted to ATC: “we seem to be having some type of difficulty here could uh you give us assistance please”. At 09:13:01, after the airplane completed the three turns, the pilot transmitted: “we’re with ya we were off getting back on course here we had a little difficulty with the auto pilot.” At this time, the airplane’s track was approaching its original course line to the Westminster VOR. At 09:13:35 the pilot requested a heading to the Frederick airport, so they could “do a stop”, and he received a clearance to fly a heading of 280 degrees. Also over the next 30 seconds, the airplane’s track stabilized at about 274 degrees magnetic. Altitude and airspeed continued to fluctuate during this time; however the pitch attitude was relatively stable when compared to the previous and subsequent pitch oscillations. At 09:14:08, the airplane again began a turn toward the left. At 09:14:46 the “next waypoint” parameter changed from EMI (the Westminster VOR) to KFDK (Frederick Municipal Airport). At 09:15:23, the pilot again reported to ATC that he was “having some problems with the autopilot”. After the left turn, the airplane did not return to a course toward Frederick, and did not maintain any course/heading for longer than about 12 seconds. Altitude and airspeed continued to fluctuate significantly, with the exception of one period of about 20 seconds where the altitude was relatively stable around 2,600 feet (pressure altitude) and the airspeed remained around 110 knots. Over the last 2 minutes of the flight, the fluctuations in altitude and airspeed appear to be somewhat periodic in nature. The last recorded data points indicated a pressure altitude of 707 feet, indicated airspeed 148 knots, and a descent rate of 6,824 fpm. AIRCRAFT INFORMATION According to FAA and airplane maintenance records, the accident airplane was manufactured in 2006. The airplane’s most recent annual inspection was completed on March 1, 2007. At the time of the inspection, the airplane had accrued 74.9 total hours of operation. The airplane was equipped with an Avidyne FlightMax Entegra Integrated Flight Deck, which included two 10.4-inch displays, one of which was the PFD and the other of which was the Multi Function Display (MFD). A set of standby flight instruments were also installed which consisted of a magnetic “whiskey” compass (attached to the center post of the windscreen), a conventional attitude indicator, conventional airspeed indicator, and a conventional altimeter (all of which were located to the left of the PFD in a vertical line). All could be used by the pilot to fly the airplane in instrument meteorological conditions in the event that the PFD malfunctioned. Additionally, the airplane was equipped with dual Garmin GNS 430 global positioning systems (GPS), and an S-TEC System 55X autopilot, with full-function heading, navigation, and altitude hold, with localizer/glideslope coupling, and altitude pre-select functions that were integrated into the PFD. Together with the audio control panel, these systems were located to the right of the PFD in a vertical line. During the most recent annual airworthiness inspection, maintenance personnel determined that the accident airplane required modification of the PFD as required by Avidyne's PFD Mandatory Service Bulletin, SB 601-00006-067. This bulletin referenced earlier alerts and requested that the PFDs be returned to the factory for an update which would “reduce the likelihood” that the PFD could present erroneous indications. According to an FAA inspector and the maintenance provider’s Director of Service , the maintenance facility was advised by the pilot that due to the amount of time required to update the unit (10 business days), and since the pilot was trading in the airplane soon, the pilot elected to defer the maintenance action until a later date. PERSONNEL INFORMATION According to FAA records, the pilot held a private pilot certificate with ratings for airplane single-engine land, and instrument airplane. His most recent FAA third-class medical certificate was issued on December 12, 2006. The pilot records also indicate that the accident airplane was the second Avidyne-equipped airplane the pilot had owned; the first airplane that he owned was a Piper PA-32-301FT. The pilot also had taken formal training at Simcom when he purchased his first Avidyne equipped airplane, and again when he purchased the accident airplane. He had accrued 546.2 total hours of flight experience of which 291.5 hours were accrued in the two airplanes. At the time of the accident, records indicated that he was IFR current and qualified. METEOROLOGICAL INFORMATION The recorded weather at Martin State Airport (MTN), Baltimore, Maryland, approximately 26 nautical miles southeast of the accident site, at 0918, included: wind 020 degrees at 3 knots, visibility 3 miles in heavy drizzle, scattered clouds at 800 feet, broken clouds at 2,400 feet, overcast at 3,000 feet, temperature 8 degrees C, dew point 8 degrees C, and an altimeter setting of 30.36 inches of mercury. Cloud tops were reported to ATC by a Southwest Airlines flight as being at 8,500 to 9,000 feet above mean sea level (msl). Witnesses reported that the cloud bases were low to the ground and it was raining. WRECKAGE AND IMPACT INFORMATION The wreckage was located in a residential area about 17 miles west of 0W3. Examination revealed that all major components of the airplane were located at the accident site. After impacting trees, the airplane came to rest on a magnetic heading of 216 degrees. An approximately 3-foot deep crater existed beneath the main wreckage. An 85-foot long debris field, oriented on a magnetic heading of 212 degrees was present. Multiple portions of tree limbs, exhibiting cut marks consistent with propeller strikes, were spread throughout the area. The engine and propeller remained attached to the airplane but were buried below ground level. All three propeller blades exhibited evidence of rotation. One blade was separated from the propeller hub approximately 1-inch outboard of the blade grip. A partial disassembly and examination of the engine did not reveal any evidence of preimpact mechanical malfunction. All passenger entry and baggage door latches were in the closed position. Both the landing gear and the flaps were in the up position. The fuel selector valve was in the left tank position. The standby attitude indicator indicated a 60-degree right bank, a 20-degree nose down pitch attitude, and evidence of rotational scoring internally. The barometric scale on the standby altimeter indicated 29.65 inches of mercury. The airspeed indicator was off-scale above 215 knots. Both wings were separated from their mounting locations and exhibited fracturing and various degrees of crush damage. The wing flaps and ailerons exhibited multiple breaks and separations and were spread throughout the debris field. The vertical stabilizer and rudder panel remained attached to their fittings. The left and right portions of the stabilator were fragmented. The center portion of the stabilator, portions of the right side anti-servo tab, and stabilator actuation mechanism remained attached to the aft fuselage. The pitch trim jackscrew was found in the full nose-down position, however; no preimpact failures or disconnects of the primary flight control system were discovered. Control continuity was established from the stabilator control mechanism to the control wheel pitch actuating mechanism; the rudder pedals to the rudder panel, and from the ailerons to the broken ends of the control cables, which exhibited evidence of tensile overload. MEDICAL AND PATHOLOGICAL INFORMATION A postmortem examination was performed on the pilot by the State of Maryland’s Office of the Chief Medical Examiner. Toxicological testing of the pilot was conducted at the FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma. The pilot's forensic toxicology report revealed that, ethanol was detected in Muscle (from sources other than ingestion), and Naproxen which is a non-steroidal-anti inflammatory drug, was detected in Liver. TESTS AND RESEARCH Component Tests Because the pilot advised ATC that he “had a little difficulty with the autopilot”, and the pitch trim jackscrew was found in the full nose-down position, both the autopilot control system, and pitch trim system, were examined. No evidence of any pre-impact malfunctions was discovered. If an autopilot malfunction had occurred, the pilot could have disconnected the autopilot system by any one of the six following actions: Pressing the AP DISC/TRIM INTR switch on the control yoke; Actuating the electric trim via the Trim Switch; Turning off the AP Master Switch; Pulling the AP Circuit Breaker; Turning off the Avionics Master switch; Turning off the Battery Master Switch. Because the autopilot computer received analog information from the PFD, investigators reviewed the differences between the interaction of the autopilot with an aligned PFD and an unaligned PFD. The review revealed that when the PFD is aligned, it provides the autopilot with the analog Vertical Speed Indicator (VSI) “bug” value set on the PFD and that the autopilot computer utilizes this value as a target when operating in either the vertical speed (VS) mode or the altitude capture mode. When the PFD is not aligned, the VSI “bug” on the PFD is visible and can be adjusted, but the PFD will only output a value of zero, along with a discrete flag, resulting in the autopilot (instead of the PFD) being in control of the vertical speed target. In this condition, the autopilot’s VS mode will attempt to hold the current vertical speed at the time the mode is activated, and the desired vertical speed would have to be adjusted using a separate knob on the autopilot control panel. A review of the Entegra Piper PA28 and PA32 EXP5000 Primary Flight Display Pilot's Guide revealed however, that it did not provide this information to the pilot regarding suppression of the bug settings when the PFD was not aligned. A turn coordinator provided the S-TEC 55X autopilot flight guidance computer with signals indicating the airplane’s turn and roll rate. Examination of the wreckage revealed that the turn coordinator was installed forward of the instrument panel where it was not visible to the pilot; therefore, the turn coordinator could not be utilized by a pilot in the event of a failure of the PFD, or used to help determine the airplane’s attitude if there was a disagreement between the displayed attitude on the PFD and the standby attitude indicator. FAA certification standards for glass panel equipped aircraft like the accident airplane do not require a turn coordinator. Examination of other manufacturer’s airplanes configured with a single PFD also revealed similar configurations with non-viewable turn coordinators. Examination of the turn coordinator did not reveal any evidence of a pre-impact failure or malfunction. The Air Data Unit (ADU) supplied the following air data to the Air Data and Attitude Heading Reference System (ADAHRS): Pressure Altitude, Calibrated Airspeed, True Airspeed, Outside Air Temperature (OAT) and Vertical Speed. Internal examination of the ADU’s pressure transducers revealed no anomalies and the pressure altitude data recorded by the PFD agreed with the pressure altitude in the recorded radar
The pilot's failure to maintain control of the airplane which was a result of spatial disorientation after takeoff into instrument conditions with an operationally degraded electronic primary flight display. Contributing to the accident were the pilot’s failure to properly utilize the airplane’s standby flight instruments, the electronic primary flight display system’s unaligned state prior to takeoff for undetermined reasons, and the pilot’s lack of knowledge of degraded autopilot functions with an unaligned primary display system.
Source: NTSB Aviation Accident Database
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