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On May 16, 2002, approximately 1727 mountain daylight time, a Grumman G-44, N700BL, registered to and operated by the pilot as a 14 CFR Part 91 personal flight, experienced a loss of engine power shortly after takeoff and subsequently collided with a residence located about one mile north of the Boise Air Terminal, Boise, Idaho. Visual meteorological conditions prevailed at the time and a visual flight rules flight plan was filed. The aircraft was substantially damaged and the two airline transport pilots received serious injuries. One person was at the residence and was not injured.
During a telephone interview and subsequent written statement, the pilot stated that he had recently purchased this aircraft and was flying it from Kenai, Alaska to Florida. On the day of the accident (third day of the trip), the flight originated in Bellingham, Washington, about 1200 Pacific daylight time and arrived in Boise approximately 1440. The pilot stated that 80.4 gallons of fuel was added to top off the fuel tanks. No oil was added. The pilot reported that after a pre-flight and engine start, he noted that "the right engine had a tendency to stall out below 1000 rpm, a condition that developed during the trip down from Alaska." A normal takeoff on runway 28 right was accomplished. Shortly after liftoff, the tower controller informed the pilot that one of the landing gear had not fully retracted. The pilot reported that he utilized the hydraulic hand pump and the gear fully retracted. The pilot stated that the aircraft was about 200 to 300 feet agl, when he then felt the aircraft yaw and noted that the rpm on the right engine was down from 2600 rpm (normal) to 1800 rpm. The pilot informed the tower controller that he was returning (for landing) and began a right downwind turn. The pilot reported that at this point he concentrated on maintaining 95 mph airspeed and did not attempt to feather the propeller or secure the right engine. The aircraft was unable to maintain altitude and continued to descend into a residential area. The aircraft collided with trees and power lines before coming to rest on the roof of a single story residence located at 2120 S. Hilton.
The pilot rated passenger reported that the pre-flight, start, and taxi to the runway were normal. Power was applied and 2,600 rpm was noted on both engines with 25-30 inches of manifold pressure. Both fuel pressures were in the normal range. After liftoff, the aircraft accelerated to 100 mph and a 500 foot/minute climb was attained. The flaps and gear were retracted, however, the gear did not fully retract and the pilot pumped the manual hydraulic handle a couple of times and the gear fully retracted. The passenger stated that just as the green "up" light illuminated and the gear was visually checked, the aircraft yawed to the right. The passenger noted that the rpm gage for the right engine was about 1,800 rpm, while the left engine was still indicating 2,600 rpm. The pilot leveled the aircraft at about 3,000 feet msl (about 130 feet agl) and stated that he was going to return to the airport. The tower controller cleared the aircraft for either a left or right downwind. The passenger stated that the pilot turned right and that during the turn, the airspeed started to bleed off down to 80 mph. The passenger pointed this out to the pilot which he then lowered the nose in an effort to maintain 95 mph, which is the minimum single engine airspeed. The passenger stated that initially the sink rate was high, but then shallowed out when the airspeed increased. The passenger thought that they were going to be able to level out just above the trees when he looked at the rpm gage for the right engine and noted that it was just above idle position. The aircraft then collided with the first tree, subsequently colliding with additional trees and power lines before coming to rest on the roof of a residence. The passenger stated that the pilot turned off the fuel and electricity to limit a fire hazard.
The pilot holds an Airline Transport Pilot certificate and is rated in single and multi-engine land and sea aircraft. The pilot was also rated in rotorcraft. The pilot reported a total flight time in all aircraft of 10,250 hours with 8,200 hours as pilot-in-command. A total flight time of 28 hours were reported in the accident aircraft make & model, with 21 hours as pilot-in-command. The pilot received his type rating in multi-engine sea aircraft on April 18, 2002, in a Grumman G-44, located in Florida. The pilot reported that all of the multi-engine sea flight time has been in the Grumman G-44.
The pilot rated passenger holds an Airline Transport Pilot certificate and is rated in single and multi-engine land aircraft. The passenger reported a total flight time in all aircraft of 9,000 hours, with 3,000 hours as pilot-in-command. The passenger reported a total flight time of 15 hours in the accident aircraft make & model, with zero hours as pilot-in-command.
Maintenance records and documents found in the aircraft were reviewed. The pilot reported that he had just purchased this aircraft and had fixed several maintenance discrepancies prior to the flight from Alaska. The pilot maintained a log of daily activity dated May 4, 2002, to the day of the accident documenting each days activities. The overhauled propellers were picked-up from the overhaul shop on May 5 and installed on the aircraft May 6, 2002. The propeller logbook indicated that the sign-off for the annual inspection certifying that the propellers had been inspected in accordance with an annual inspection and determined to be in an airworthy condition was on May 8, 2002. Both engine logbooks also indicated an annual inspection sign-off on May 8, 2002. The airframe logbook indicated an annual inspection sign-off on May 9, 2002.
Additional discrepancies noted in the daily log indicated that on May 6, the batteries were found low and the engines would not start. The batteries were removed and recharged. On May 7, the engines were started but it was found that the tachometer for the left engine (number 1) was inoperative. Also the wheel bearings were making noise and it was found that the right inboard wheel bearings were dry and rusted. On May 8, the aircraft was jacked up onto a cradle and the landing gear was extended and retracted using the hand pump. On May 9, new wheel bearings were installed, and the engines were started in preparation for a flight. During the run-up a "bad mag check" was experienced and the flight was cancelled. The spark plugs were cleaned and gapped, along with installing new tires. On May 10, an exhaust leak was fixed, along with the door latch. The first flight after the annual inspection signoff was on this day. After the one hour flight, the daily log indicated "came back with #1 tach, engine mixture #2, #1 engine barrel seal, possible att gyro problem." A second 1.2 hour flight was flown later in the day. The daily log indicated "came back with flap indicator, #1 tach, tail wheel strut, left elevator fabric." The final entry for this day indicated, "Fixed everything and ran it up at 2230. Checks good." On May 11, the daily log indicated that, "tach problem is back - no fly." The entry indicated that most of the day was used trying to fix the problem with no success. A decision was made to rewire the tach, which would have to be done in Anchorage. On May 12, the daily log entry indicated that a person was found to build the wire harness. On May 13, the new wire harness was installed. A 1.5 hour flight was made. The entry indicated, "no problems." On May 14, a .5 hour flight was flown with no problems noted. At 1255, the flight departed from Kenai, Alaska, to Yakutat, Alaska, continuing on to Sitka, Alaska. A total of 5.4 hours of flight time was logged. No indication of problems were noted in the daily log. On May 15, the flight departed from Sitka to Prince Rupert, Canada, a total of 2.5 hours flight time. The flight continued on to Port Hardy, Canada, a total of 1.5 hours flight time, continuing on to Bellingham, Washington. The page in the daily log was torn and part of the page was missing. The total flight time for this leg is unknown. No discrepancies were noted on the existing page section. On May 16, the flight departed from Bellingham for Boise, Idaho. A total flight time of 3.4 hours were logged. No discrepancies were noted.
A work order Invoice was found among the records. Later the mechanic provided the maintenance worksheet of discrepancies and corrective actions. The invoice indicated that a pre-purchase inspection began on February 22, 2002, by Aero Maintenance, Soldotna, Alaska. The work order identified a description of the work to be accomplished for the annual inspection. One of the items indicated "purge fuel systems." On May 9, the invoice indicated, among other things, "general engine inspection" was accomplished. The maintenance worksheet dated February 24, 2002, indicated a discrepancy that stated, "Old fuel in tanks and systems." The corrective action stated, "Drain fuel tanks - drain and clean fuel strainers. Drain fuel line to servos. Service tanks with 5 gal ea. for gnd run and sys. checks."
Airframe logbooks dating back to 1963 were reviewed. Throughout the years, annual inspections were accomplished on the aircraft. An entry in 1971, indicated "replaced metal wings with original fabric type wings without fuel tanks. Repaired main fuel tank adapter holes with riveted .060 2024-T3 alm. covers." No other entries were found indicating work accomplished to the fuel tanks. On June 11, 1998, the last annual inspection accomplished on the aircraft prior to the current annual inspection, indicated that the gascolator(s) were cleaned at a total airframe time of 3787. The May 9, annual inspection sign-off indicated a total airframe time of 3791.5 hours.
Records obtained from the Federal Aviation Administration revealed that the pilot, on the day of the accident, filed a visual flight rules flight plan from Boise to Kemmerer, Wyoming (EMM), via Logan, Utah (LGU).
At 1716, the pilot notified Boise ground control that he was ready to taxi. The controller instructed the pilot to taxi to runway 28 right. At 1723, the pilot contacted Boise local control and informed the controller that he was ready (for takeoff), but needed a minute for wake turbulence. The controller instructed the pilot to taxi into position and hold, and to notify him when he (the pilot) had enough time. At 1724, the pilot notified the controller that he was ready to go. The controller cautioned the pilot as to the wake turbulence and cleared the aircraft for takeoff, approving a left turn after departure. At 1726, the controller notified the pilot that it did not appear that the right main landing gear was fully retracted. The pilot responded that they may have to return for landing. The controller responded that it was the pilot's choice if he wanted a right or left downwind. The pilot informed the controller that he would do a right downwind. At 1726:58, the controller broadcast, "he's going to crash." At 1727:07 and 1727:21 two mayday calls were received. At 1727:23, the controller broadcast, "Grumman 0BL, if you've landed safely and can hear me, we have rung the crash phone out for you."
WRECKAGE AND IMPACT INFORMATION
Air Traffic Control personnel and witnesses in the area reported that they observed the aircraft traveling at a low altitude northbound from the airport when it collided with trees, and a power line in front of a residence where the aircraft subsequently came to rest on the roof of a single story residence. Local law enforcement personnel reported that the wreckage debris was confined to the area immediately around the residence. The power pole/lines and trees were about 20 to 25 feet in height.
The fuselage section remained intact with the aft empennage, just forward of the horizontal stabilizer, partially detached. The nose section was displaced to the left. Both wings remained attached to the wing root and both engines remained intact in their respective nacelles. Both propeller assemblies remained attached to their respective crankshaft. No fuel spill was reported.
Broken power line cables were wrapped around the right side propeller spinner assembly. Evidence of contact with the quarter inch cable was noted on propeller blade "A" near the blade root and traveled outboard about nine inches. Aft bending and pitting was noted at the blade tip. Propeller blade "B" displayed aft bending to the outboard 12 inches of the blade. Minor chordwise scoring was noted to the outboard eight inches of the tip. The right wingtip float had separated. The flap remained attached to its respective hinges. The aileron was bent and damaged at the inboard hinge.
The left engine propeller blade "A" was missing approximately four inches off the blade tip. Chordwise scratches and minor gouging along the leading edge with severe gouging near the tip was noted. Six inches of a black material presumably from the roof material was noted on the blade. Propeller blade "B" was also missing approximately four inches off the blade tip. Severe leading edge gouging was noted near the tip. The blade displayed a forward bending. The spinner was pushed aft and deformed. The outboard three feet of the wing tip had separated along with the wing tip float. The flap remained attached to its hinges. The aileron remained attached at the inboard hinge. The aileron was bent aft.
The empennage section partially separated just forward of the horizontal stabilizers. The left horizontal stabilizer and elevator were intact, along with the stabilizer strut. The trim tab remained attached at the hinges. The right side horizontal remained attached at the root. The elevator remained attached at the hinges. The outboard section of both the stabilizer and elevator was bent downward. The trim tab remained attached at its hinges and undamaged. The stabilizer strut remained attached to the fuselage side and had separated at the attach point on the stabilizer side. Duct tape was noted along the leading edge of the elevator from the tip inboard about two feet. The pilot later confirmed that the skin had come loose in flight while en route from Alaska. The pilot had applied the duct tape as a temporary patch.
The vertical stabilizer and rudder, with rudder trim tab, remained intact. Upward crushing was noted to the bottom of the rudder.
Control cables from the forward fuselage section and the aft empennage section had been cut at the accident site during recovery. The control cables remained attached to their respective aft attach points for the rudder, elevator and trim tabs.
TESTS AND RESEARCH
On May 21, 2002, the aircraft and right engine was inspected. The cowling was removed and a visual inspection of all accessories and fuel lines noted no abnormalities. After the quarter inch power line cable was removed from around the propeller spinner, the crankshaft rotated easily by hand. Gear and valve train continuity was verified and all cylinders developed compression. The lower spark plugs were removed and normal operating signatures were noted. Both magnetos were removed and rotated via a hand drill. All towers produced spark. Fuel lines from the gascolator to the engine driven fuel pump, fuel control unit and manifold contained a trace amount of fuel. The manifold screen was clear of contaminants with a trace amount of fuel. The diaphragm was pliable. The finger screen to the fuel control unit was clear with minor bits of metal shavings noted. The engine driven fuel pump was removed and disassembled. The unit components were intact with no notable damage. The electric fuel pump was energized and appeared to function normally. The fuel line to the fuel strainer was intact. The fuel filter bowl was a clear material which allowed a visual inspection of the filter prior to disassembly. The bowl was filled with blue colored fuel. Upon closer inspection it was noted that the filter was contaminated with heavy deposits of metal flakes accumulated at the top end of the filter. The filter itself was a brown colored tightly woven material. The entire filter was covered with metal flakes of various sizes and shapes. Visually and under magnification, many of the metal flakes were corkscrew in shape. The right side fuel tank was drained of the fuel. After the fuel was drained, the fuel tank sump was removed. The sump tank contained additional metal flakes of various sizes, to include corkscrew shapes, screws, washers, and chunks of pink colored sealant material. The left side fuel tank was also drained. The sump tank was clear of contaminants. The left side gascolator bowl was a solid metal and not see through. The bowl was removed and the filter was a metal screen. The screen was clear with no contaminants noted.
The wreckage was released to the owner's representative on June 5, 2002. At the time, the wreckage was located at Western Aircraft, Boise, Idaho.
The FAA Approved Airplane Flight Manual for the accident aircraft indicated in the Emergency Procedures section under Engine Failure, that if an engine failure occurs after the airplane is airborne, and single engine climb speed attained, the inoperative engines throttle should be closed, the propeller feathered, mixture control to idle cut-off, the ignition switch and gas supply off. Airspeed should be maintained between 94 mph to 97 mph. The Single-Engine Rate of Climb performance chart indicated that for the calculated density altitude at the time of 4,095 feet (temperature 21 decrees C, Boise Air Terminal airport elevation 2,868, altimeter 30.04"Hg), a rate of climb of approximately 75 feet/minute was indicated.