Piper PA-31-350 Navajo Chieftain

While descending from 5,000 feet to 3,000 feet, the pilot informed ATC that the left engine had failed and the engine cowling was open. The crew said that after feathering the left propeller, and with the right engine at full power, they could not arrest a 300-500 fpm rate of descent. The crew informed ATC that they would be landing in the water. All the occupants exited the airplane from the left front pilot's emergency door. The victims were in the water for approximately 30 minutes before being rescued. One of the passengers was in cardiac arrest when he was retrieved from the water. Examination of the left engine revealed that the #2 cylinder had separated from the engine in flight as a result of high stress fatigue cracking of the cylinder hold down studs and the #3 main bearing thru-studs. The fatigue in the studs occurred as a result of the cylinder fastener preload forces either initially inadequate or lost during service. Maintenance records indicated that the thru-stud was replaced 80 service hours prior to the accident. Examination of the cylinder hold down studs and the #3 main bearing thru-studs revealed that they were improperly torqued, resulting in low initial preload on the fasteners. Incorrect installation of the oversize thru-studs, per existing service information, could have also been a factor in the improper torquing of the studs. The locations of the fatigue origins and the edge worn into the deck indicate that the upper studs were probably the first to fail, allowing the cylinder to rock on the lower rear corner of the cylinder flange.

After deplaning passengers at Thief River Falls after an air taxi flight, the pilot was reportedly anxious to return to his base in Minot to prepare for another trip the following day, and left for the return trip within a few minutes after his arrival at Thief River Falls. There was no record of a weather briefing. Observations of Doppler radar by the University of North Dakota, and a Safety Board meteorological study, show that the airplane had penetrated a thunderstorm when control was lost. The airplane had encountered the center of a microburst, and was located directly under the downdraft.

Bearskin flight 362, a Fairchild Swearingen Metro 23, departed Red Lake, Ontario, at 1300 central daylight saving time (CDT), with two pilots and one passenger on board, en route to Sioux Lookout on an instrument flight rules (IFR) flight plan. At approximately 30 nautical miles (nm) north of Sioux Lookout, the flight was cleared by the Winnipeg area control centre (ACC) for an approach to the Sioux Lookout airport. Air Sandy flight 3101, a Piper Navajo PA-31, departed Sioux Lookout at 1323 with one pilot and four passengers on board en route to Red Lake on a visual flight rules (VFR) flight. The pilot of Air Sandy 3101 reported clear of the Sioux Lookout control zone at 1326. No other communication was heard from the Air Sandy flight. At 1315 the Winnipeg ACC controller advised the Sioux Lookout Flight Service specialist that Bearskin 362 was inbound from Red Lake, estimating Sioux Lookout at 1332. At 1327, Bearskin 362 called Sioux Lookout Flight Service Station (FSS) and advised them they had been cleared for an approach and that they were cancelling IFR at 14 nm from the airport. At 1328, as Sioux Lookout FSS was giving an airport advisory to Bearskin 362, the specialist heard an emergency locator transmitter (ELT) emit a signal on the emergency frequencies. Moments later, the pilot of Bearskin 305, a Beechcraft B-99 in the vicinity of Sioux Lookout, advised the specialist that he had just seen a bright flare in the sky and that he was going to investigate. The pilot of Bearskin 305 stated that the flare had fallen to the ground and a fire was burning in a wooded area. A communications search was initiated to locate Bearskin 362, but the aircraft did not respond. A Search and Rescue aircraft from Trenton, Ontario, and an Ontario Ministry of Natural Resources (MNR) helicopter were dispatched to the site. The source of the fire was confirmed to be the Air Sandy aircraft. The MNR helicopter noticed debris and a fuel slick on a nearby lake, Lac Seul. It was later confirmed that Bearskin 362 had crashed into the lake. (See Appendix A.) The two aircraft collided in mid-air at 1328 during the hours of daylight at latitude 50º14'N and longitude 92º07'W, in visual meteorological conditions (VMC). All three persons on board the Bearskin aircraft and all five persons on board the Air Sandy aircraft were fatally injured.

The charter flight was on a return tour trip after landing at the Grand Canyon National Park Airport. No fueling or maintenance was performed on the airplane while it sat on the ground for three hours. Shortly after takeoff from runway 21, the pilot transmitted that he had a problem and was declaring an emergency. He then stated '...I'm single engine right now....' The airplane was observed to be 100-200 feet above the terrain at the time. It continued flying for about 6 minutes, turning onto a crosswind, downwind, and then a right base leg for runway 21 before colliding with trees about 2.5 miles northeast of the airport. The airport is located in terrain that slopes upward from south to north and west to east. Winds were gusting to 29 knots. The density altitude was 6,870 feet. Examination of the suspect left engine did not reveal any evidence of failures or malfunctions. The investigation revealed deficiencies in the Federal Aviation Administration's oversight of the airline's maintenance program, and in the airline's extension of the time-in-service interval of the engines. The airline's AAIP does not require a maximum rated power check of the engines as required by the engine manufacturer's service instruction. In addition, the TBO of the engines had been extended from 1,800 to 2,400 hours.

During an international cross country flight the private pilot, certificated single engine land, experienced a dual engine power loss as he was being vectored to the Brownsville Airport. Following the accident the aircraft was examined by a Federal Aviation Administration inspector who found that there was fuel in the left fuel tank and that the fuel selector was in the right tank position. The pilot had reported, prior to loss of engine power, that he had low fuel indications in the right tank and that he needed a vector to Brownsville. The aircraft was landed in rough and uneven terrain, resulting in damage to the structure and wings, approximately 1/2 mile short of the runway.

Fifteen minutes after takeoff from Nairobi-Wilson Airport, while flying in marginal weather conditions, the twin engine aircraft struck the slope of a mountain located in the Ngong Hills, about 21 km southwest of Wilson Airport. The aircraft was destroyed upon impact and all five occupants were killed.

The crew departed Jayapura-Sentani Airport on a cargo flight to Oksibil. En route, the twin engine aircraft disappeared, maybe in a mountainous area located north of Oksibil. The wreckage was never found.

After landing at Siwandu Airfield, the twin engine airplane collided with a giraffe. The animal was killed and the aircraft was destroyed. The pilot escaped uninjured.

The captain had ILS glideslope data available during the approach but did not fly the ILS glideslope. The partial obscuration of the airport environment, due to ground fog, contributed to the captain's failure to recognize that the airplane was high on both his approach and landing. The destruction of the airplane and the resulting occupant injuries were a direct result of the collision with the blast fence. FAA interaction and communication with local communities, although persistent, were unsuccessful in gaining support for runway safety area improvements and for the installation of approach lighting for runway 6. The passenger seats had been improperly assembled using unapproved parts, and seat belts had been installed incorrectly.

The ATP and his passenger were en route to pick up a patient for transport to a VA hospital. The destination airport was uncontrolled, and VFR only. The pilot cancelled with ATC and reported the field in sight. The airport was reporting VFR conditions, but rising, mountainous terrain existed to the northeast, and local authorities reported that the top third of the mountain was obscured in clouds during the morning of the accident. After cancelling IFR, no subsequent radio calls were received from the flight, and the flight did not arrive at its destination. The wreckage was found several hours later near the crest of holston mountain, 1/2 mile east of the Holston mountain VOR. An examination of the wreckage indicated the aircraft impacted upsloping, wooded terrain, while at a climb angle of 8°. Disintegration of the wreckage was indicative of a high speed impact. No evidence of mechanical malfunction or failure was found during the examination of the wreckage. Both occupants were killed.