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On June 17, 2004, at 1746 mountain daylight time, a WSK PZL Mielec (Dromader) M-18A, N8214J, collided with terrain following a fire retardant drop near St. George, Utah. New Frontier Aviation, Inc., owned the airplane. The Bureau of Land Management (BLM), U. S. Department of the Interior (DOI), was operating the airplane under the provisions of 14 CFR Part 91 with a restricted category Federal Aviation Administration (FAA) airworthiness certificate as a public-use fire suppression flight. The airline transport pilot, the sole occupant, sustained fatal injuries; a post crash fire destroyed the airplane. The local flight departed St. George about 1730. Visual meteorological conditions prevailed, and a BLM flight plan had been filed. The primary wreckage was at 37 degrees 19.562 minutes north latitude and 113 degrees 36.818 minutes west longitude at an estimated elevation of 5,900 feet.
The BLM provided an airborne AirTac, who controlled the air assets working a fire. The AirTac instructed the tankers on where to drop. The tankers, including the accident pilot, had been making drops in a pattern similar to an inverted L with the short axis pointing to the right. AirTac instructed the accident pilot to extend the drop line (the short axis of the inverted L). The drop line heading was about 218 degrees.
The pilot was to fly downwind parallel to and in the opposite direction of the drop line, which was to his left. The pilot would then turn 90 degrees to the left (base turn), and then make another 90-degree left turn onto final. Drop altitude was about 100 feet above ground level (agl), and the ground sloped down about 20 degrees throughout the drop zone.
The AirTac said that the pilot called for a dry run; the second pass was going to be a drop. On the second pass, the pilot said that he overshot final, and was going around. On the third pass, the pilot called downwind, base, and final. The pilot made no other transmissions, and did not indicate that he was having any problems.
Witnesses observed the retardant exit the airplane. However, the drop was not at the desired point, and not distributed in an even line as the pilot's previous drops had been. The drop angled about 10 degrees to the final approach course. The drop ended at the convergent point of the L (beginning of the drop line) rather than starting at the end of the line. The drop pattern was wide and heavy at the beginning, and narrow and thin at the end.
About 2 seconds after the drop, one ground witness and one airborne witness reported that the nose of the airplane pitched up slightly, which they said was normal after a drop. All witnesses reported that the nose of the airplane then pitched down about 45 degrees. The airplane maintained this attitude until ground impact, and the witnesses observed an immediate fireball.
A review of FAA airman records revealed that the pilot held an airline transport pilot certificate with a rating for airplane multiengine land. The pilot held a commercial pilot certificate with a rating for airplane single engine land. The pilot held a certified flight instructor (CFI) certificate with ratings for airplane single engine land, multiengine land, and instrument airplane. The pilot held a ground instructor certificate for instrument and advanced.
The pilot held a second-class medical certificate issued on February 27, 2004. It had the limitations that the pilot must wear corrective lenses.
The operator reported that the pilot had total flight time of 21,000 hours, with an estimated 60 hours in this make and model. He noted that the pilot flew crop dusters, gave flight instruction, and was a designated check airman for the FAA.
The airplane was a WSK PZL Mielec (Dromader) M-18A, serial number 1Z020-21. Fire destroyed the airplane's logbooks, which were in the airplane.
The airplane had been modified in accordance with Supplemental Type Certificate (STC) number SA01276AT. This STC increased the maximum takeoff gross weight from 9,260 pounds to 11,700 pounds. It limited the airplane to the Restricted Category, and for the special purpose operation of fire suppression of forest fires. The STC required installation of a placard of limitations within clear view of the pilot. The placard contained airspeed limitations; it noted a stall speed of no flaps at 93 mph indicated airspeed (IAS), 106 mph minimum operating speed, and a maximum drop speed of 112 IAS.
The operator reported that the airplane also had vortex generators installed in accordance with another STC. He stated that without the vortex generators, the airplane would experience a rapid wing drop if the pilot pulled too hard in a turn, and stalled the wing. However, with them installed, the airplane was very docile when it stalled. He said that the airplane would significantly buffet prior to stalling.
The operator estimated a total airframe time of 2,500 hours. The engine was a WSK-PZL-K. The operator estimated that the engine had about 50 hours since overhaul. He reported that this engine was a KIBB, which had modifications that upped the engine horsepower.
Fueling records at St. George established that the last fueling of the airplane occurred at 1645 on June 17, 2004, with the addition of 120.6 gallons of 100LL-octane aviation fuel.
The airplane was in contact with AirTac on frequency 126.825.
WRECKAGE AND IMPACT INFORMATION
Investigators from the Safety Board, the FAA, and the Office of Aircraft Services (OAS) examined the wreckage at the accident scene.
The first identified point of contact (FIPC) was two parallel ground scars that were 11 feet 6 inches apart. The FIPC was 30 feet past a 15-foot-tall cedar tree, which had no broken limbs. Five feet from the left ground scar, at its 7-o'clock position, was a 4-foot-tall tree that had fire damage, but no broken branches. The landing gear for this airplane are 11 feet 6 inches apart. Eleven feet forward of the FIPC ran a ground scar that was 58 feet long. This scar was perpendicular to the parallel scars and ran through the principal impact crater (PIC). The wing span for the Dromader is 58 feet. The left end of this ground scar contained red lens fragments; green fragments were forward of the right end. The PIC contained two propeller blades that separated from the hub.
The debris path was along a magnetic bearing of 210 degrees. The main wreckage came to rest inverted about 155 feet from the PIC. The orientation of the inverted fuselage was 040 degrees. The main wreckage contained the engine, wings, flaps, fuselage, and empennage. The wings sustained mechanical and thermal damage. Both wing leading edges exhibited similar crush damage. They were both crushed aft to the spar.
The left aileron separated, and was about 65 from the PIC. The right aileron separated, and was about 10 feet from the right wing. The fracture surfaces for both ailerons were angular and jagged. One separated propeller blade was near the left wing; the fourth propeller blade remained attached to the hub. The right main landing gear separated, and was several hundred feet downhill from the main wreckage.
MEDICAL AND PATHOLOGICAL INFORMATION
The Utah office of the Medical Examiner completed an autopsy. The FAA Toxicology and Accident Research Laboratory performed toxicological testing of specimens of the pilot. The analysis of the specimens detected no carbon monoxide or cyanide detected in blood, and no drugs tested for in the liver.
The report contained the following results: no ethanol detected in the liver, 50 (mg/dL, mg/hg) ethanol detected in muscle; 18 (mg/dL, mg/hg) acetaldehyde detected in liver; 6 (mg/dL, mg/hg) acetaldehyde detected in muscle; 1 (mg/dL, mg/hg) N-butanol detected in muscle; and 4 (mg/dL, mg/hg) N-propanol detected in muscle. The report noted that the ethanol found was from postmortem ethanol formation and not from the ingestion of ethanol.
TESTS AND RESEARCH
The FAA, New Frontier Aviation, and the OAS were parties to the investigation.
Investigators examined the airframe and engine at Air Transport, Phoenix, Arizona, on June 22 and 23, 2004. The accessories sustained thermal damage, and none of these components could be tested.
Investigators examined the flight controls. The elevator and rudder remained attached to the airframe. The top of the rudder and vertical stabilizer sustained some vertical crush damage during the nose over. The IIC traced the rudder cables from the control surface to the cockpit attachment fitting; fire consumed the airframe structure in this area.
Push-pull tubes operate the elevator. Fire consumed the forward tubes. The aft push-pull tube remained attached to the control surface. It moved freely, and the control surface moved freely in conjunction with this movement. The IIC located the control stick; fire consumed its mounting structure. Two intermediate elevator connectors remained attached to the airframe, but fire consumed the push-pull tubes. The forward intermediate connector contained the elevator up stop.
Push-pull tubes operate the ailerons. Fire consumed the push-pull tubes for both ailerons in the wing root area near the cockpit.
The left aileron's operating arm fractured in an irregular pattern. Its push-pull tubes remained connected from the operating arm to the wing root area. The fracture surface in the root area was irregular, angular, and the tube flattened. The operating arm followed movement of the inboard piece of tube.
The right aileron's operating arm fractured in an irregular pattern. A 2-foot section of the outermost push-pull tube fractured and separated. This tube section buckled; the fracture surfaces bent over and the tubes had flattened. The other push-pull tubes remained connected to the wing root area and moved freely. The root separation surface was angular and irregular.
From July 12-15, 2004, technicians at Air Response, Inc., Mesa, Arizona, examined the engine.
The propeller shaft showed a prominent bend occurring at the 3-inch mark, and a twist in the vertical splines starting at the 5-inch mark and ending at the 8 3/4-inch mark. The shop supervisor determined that the bend and twist in the splines on the propeller shaft were due to ground contact at a high power setting. He stated that if the engine was not producing power or had little power, these type indications would not be present. Also supporting his analysis was the visible twist damage on the splines on the end of the accessory starter drive shaft. These prominent twists were an indication of high power being applied by the engine to the accessory starter drive shaft when the propeller stopped due to ground contact.
The M-18 operator's manual, supplement No. 16A, 4.19(2), discussed the airplane's handling characteristics immediately after retardant release. It indicated that, with the sudden shift in CG, the airplane would pitch up, and airspeed could decrease 12 mph. Stall speeds with the vortex generators installed varied from 73 mph in the clean configuration to 72 mph with full flaps.
Interviews with other Dromadier pilots indicated that drop techniques varied. Some pilots flew at airspeeds of 85 to 90 mph to lesson the pitch up on pull out. Pilots varied the amount of flaps that they used during the drop. Several experienced pilots stated that is was possible that pilots with little experience in the airplane could "get behind" the airplane, and encounter a situation that was difficult to control, especially at low altitudes and airspeeds.
The IIC released the wreckage to the owner's representative on October 4, 2004.