We've just about come to the end of another year in which the NTSB continued to fill its files with accident reports that read suspiciously like many of the thousands it already has on file. Among the immutable truths in aviation is that an aircraft won't stay aloft without airspeed, and pilots who fail to properly manage that element are in for a rude awakening. Even the growing sophistication of aircraft in the general aviation fleet won't help in risk management and accident avoidance when fundamentals of flight are overlooked. It doesn't matter whether you're flying a Cub or an Airbus, you need sufficient airspeed so the airplane's wings will continue to produce adequate lift and the control surfaces will still provide effective control. A recent batch of finished investigations from the NTSB contained three accidents in which lack of adequate airspeed played a critical role. Adding to the airspeed enigma is that the accident aircraft represented here required different levels of training and skill, and the pilots involved represented a wide spectrum of experience.
The twin-engine airplane was on a flight from White Plains, N.Y., with a planned destination of Portland, Maine. Earlier in the day, it had flown from Portland to Nantucket, Mass., then to White Plains. At about 6:15 p.m., while it was still daylight, the airplane crashed into a house near Biddeford, Maine. The ATP-rated pilot was killed. The pilot had logged 5,010 total hours with 120 hours in Cessna 402B aircraft. Visual meteorological conditions prevailed.
While airborne and receiving flight following services, the pilot asked ATC to change his destination to the Biddeford Municipal Airport. The pilot was subsequently advised by ATC that his destination had been updated and radar services were being terminated. He was told to squawk 1200 (VFR). FAA radar data revealed that the airplane overflew the south end of the Biddeford Airport at approximately 1,000 feet MSL and turned left, as if entering the left downwind leg of the airport traffic pattern. However, it continued well beyond the point at which a turn to a left base would have been made. When it was approximately two miles from the approach end of runway 24, the airplane was observed on radar turning right and completing a loop across the ground, resulting in a reversal of direction. The airplane then maneuvered slightly to just about line up with the extended centerline of the runway, although it wasn't holding a steady heading. The last radar data indicated an altitude of 400 feet MSL and a ground speed of 69 knots.
The airplane impacted four trees. It came to rest on the roof of a house that was located approximately 1,491 feet to the northeast of the runway 24 threshold. A fire broke out. The left engine was in the house. The right wing and engine were visible above the roof line. The right main landing gear was in the down and locked position. The left main and nose gear were found in the residence.The wing flaps were found in the extended position.
The engines were sent to the manufacturer in Mobile, Ala., for examination. The left engine was too damaged for a test run. It was disassembled and no pre-accident mechanical malfunctions or failures were found that would have precluded normal operation.
The right engine was examined and mounted on an engine test stand. Approximately 20 minutes into the test, the engine sustained a partial loss of power. Additional testing determined that O-rings in the engine's throttle and control assembly had been improperly installed.
According to documentation for the airplane, the minimum approach speed with both engines operating at gross weight of 6,200 pounds is 95 KIAS. For a normal landing at a weight of 4,300 pounds, the airplane should be at 79 KIAS when passing over a 50-foot obstacle prior to the runway. However, with one engine out, the minimum control speed is 82 KIAS.
According to the FAA's Airplane Flying Handbook: "If an engine fails below Vmc while airborne...the final approach should be made with power and at a speed recommended by the manufacturer, but in no case less than critical engine-out minimum control speed (Vmc)."
The NTSB determined that the probable cause of this accident was that the pilot didn't maintain minimum controllable airspeed while on final approach with a partial loss of power in the right engine, which resulted in a loss of control. Contributing to the accident was the partial loss of engine power in the right engine due to the improperly installed O-rings in the engine's throttle and control assembly.
A Piper PA-24 Comanche crashed about 450 yards north of the approach end of runway 30 at the Ernest A. Love Field, Prescott, Ariz. The pilot and passenger were fatally injured. A post-impact fire broke out. The planned destination was unknown.
Witnesses located at various points on the airport told investigators that during its initial climb, the airplane didn't appear to be more than 150 or 200 feet above the ground. The witness reports agreed that the airplane was "slow," was flying at a high angle of attack, and at times porpoising in the air. When the airplane had reached a point above the intersection of runways 21L and 30, it was in a shallow left bank that continued to increase before impacting the ground and bursting into flames. The witnesses also reported that the landing gear had been retracted prior to the airplane initiating the left bank. Two witnesses reported hearing a strong engine sound while on the takeoff initial climb; however, they also reported that at some point they weren't able to hear the engine.
The weather observation at the time of the accident included wind from 200 degrees at 9 knots gusting to 19 knots, temperature 32 degrees C., dew point -08 degrees C. and a calculated density altitude of 7,896 feet.
According to the FAA, the flight had been cleared for a full-length takeoff on runway 21L. Tower control personnel reported that at the intersection of runways 21L and 30, the pilot stated, "Comanche zero four Papa has to come back." The controller cleared the pilot to land on runway 30. There were no further transmissions from the pilot. Runway 21L was 7,626 feet long and 150 feet wide. The field elevation is 5,045 feet.
The private pilot had logged a total of 750 flight hours.
The NTSB determined that the probable cause of this accident was the pilot's failure to maintain an adequate airspeed while maneuvering to return to the runway at a high-density altitude, which resulted in an aerodynamic stall.
A Raytheon G36 (Beechcraft Bonanza) struck a building and crashed into a parking lot near Hawthorne Municipal Airport, Hawthorne, Calif. An ATP-rated pilot, who also was an instructor, was conducting a demonstration flight for the private pilot on board and a passenger. This was the third time the private pilot had received a demonstration flight in the airplane. The first two times were with representatives of the manufacturer. The instructor had a total time of 3,500 hours, while the private pilot had a bit over 200 hours. All three occupants were killed in the accident. Visual meteorological conditions prevailed.
The airplane had taken off, executed a full-stop landing and taxied back for another takeoff. During the second takeoff roll, the instructor radioed the local tower controller that the airplane had an open door and they were aborting. After tending to the door, a successful takeoff was executed. The aircraft remained in the pattern and was lined up on final for another landing when the pilot radioed the controller that they were going around, but didn't say why.
Witnesses reported that, as the airplane was climbing upwind during the go-around, it made a left turn followed by a hard right turn. A witness observed the airplane trailing black smoke and reported the wings were rocking.
The airplane struck the building's rooftop and a wall approximately 45 feet high, then descended to a parking lot.
The airframe, engine and turbocharging system were examined with no mechanical anomalies identified that would have precluded operation. However, examination of the spark plugs and cylinders indicated that the engine was running with an overly rich fuel/air mixture, which would be consistent with the witness statements of black exhaust coming from the airplane. The electric fuel boost pump switch is located next to the landing gear selector handle. The G36 Pilot Operating Handbook cautions that use of the electric boost pump during normal operations can cause an overly rich mixture, possibly flooding the engine. It says the boost pump is designed for use during starting and emergency operations only.
The NTSB suggested that if either pilot inadvertently activated the fuel boost pump while attempting to retract the landing gear during the go-around, it could have resulted in a temporarily rich mixture, reducing the available engine power and distracting the pilots.
The NTSB determined that the probable cause of this accident was the pilot's failure to maintain an adequate airspeed during a go-around, which resulted in a loss of airplane control. Contributing to the accident was the inadvertent activation of the fuel boost pump during the attempted go-around.
Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other news concerning the National Transportation Safety Board. To subscribe, write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, N.Y. 10602-0831.