Piper PA-31-350 Navajo Chieftain

On 1 November 1997 at 09:46 hours 5H-AZM took off from Nairobi Wilson airport, for a visual flight rules flight to Zanzibar International Airport, Tanzania. It was carrying one pilot and some cargo. There were no passengers. The flight plan indicated that the aircraft had 0330 hours of fuel on departure. The pilot planned' to fly a direct route to Zanzibar with Dar-es-salaam International airport as his alternate aerodrome. After take off from Nairobi Wilson, the flight transited the southern axis lane of the Nairobi control Zone to the zone boundary. The pilot checked the Nairobi zone boundary with Nairobi Wilson Tower and was instructed by air traffic control to contact the Nairobi Control Centre. No contact was reported established by Nairobi Control with 5H-AZM. 5H-AZM contacted the Kilimanjaro Control Tower at 10:20 hours and passed his own ward estimates as Flight Information Region 10:25 hours and arrival at Zanzibar at 11:40 hours. 5H-AZM was advised that there was no reported traffic for the flight in the Kilimanjaro Terminal Control area at 'the VFR flight level 115, and at the same time instructed the aircraft to contact Dar-es-salaam Control on 119.6 MHz when in range. No further transmission was received from the aircraft. It also failed to arrive in Zanzibar. Unfruitful formal searches (involving communications, aerial and ground searches) were mounted on 3 November 1997 along the probable route area in Kenya and Tanzania. The formal search was terminated on 4 December 1997 and there after the missing aircraft incident was considered to be an 'accident. Wreckage was eventually located in the Kibo Crater near the summit of Mount Kilimanjaro in Tanzania on 28 August 2003, almost six years later. The wreckage of the Piper PA 31-350 was found at 15,400 feet on the Kibo wing. It was also 30 nautical miles west of its projected track. The aircraft had earlier been cleared to climb from 9,500 feet to 11,500 feet under visual flight rules.

The aircraft was being operated on a trans-Pacific ferry flight. A special flight permit authorized a gross weight increase and ferry fuel tanks had been installed along with long range communication and navigation radios. The pilot reported that when 85 miles from the departure airport, the right engine failed and he was unable to restart it. Power from the remaining engine was insufficient to maintain level flight at the overweight condition and the pilot permitted the aircraft to drift down until it was necessary to ditch in the ocean 28 miles offshore. The pilot had departed and returned to Hawaii twice previously. The first time he returned due to an oil leak on the left engine, and the second time because of a loose window. A mechanic who repaired the window reported that the left engine appeared to still be leaking oil. Both pilots told the FAA inspector that the oil leak had been repaired.

The aircraft, a Piper PA-31-350 Navajo Chieftain (hereafter referred to as a Chieftain), took off at 1113 Atlantic daylight saving time on a charter flight from Port-Menier, Quebec, to Bangor, Maine, with one pilot and seven passengers on board. As the aircraft was approaching Charlo, New Brunswick, the pilot reported to Moncton Air Traffic Control Centre that his aircraft had a rough-running engine, and that he would be making an emergency landing at Charlo airport. While the pilot was apparently manoeuvring to land the aircraft, it crashed three miles west of the runway, in the community of Eel River Crossing. All eight occupants of the aircraft received fatal injuries.

Crashed in unknown circumstances in a mountainous area near Sabie. Occupant's fate unknown.

A witness heard the aircraft pass King Island aerodrome at 0455 EST at the same time as he noticed the pilot-activated 10/28 runway lights illuminate. The pilot reported to Melbourne Control that he would be completing a runway 10, non-directional beacon (NDB) approach. A short time later he broadcast that the aircraft was at the minimum descent altitude, which is 640 feet above mean sea level (AMSL) for a runway 10 NDB approach. He also broadcast that there was a complete cloud cover. The aircraft did not enter a missed approach procedure but was heard to fly towards the south-east from overhead the NDB, which is located 1.3 km south-south-west of the centre of runway 10/28. A second witness, located near the NDB site, reported observing the aircraft's lights to the south-east. At 0507 a farmer heard the aircraft pass low over his house shortly before it crashed into trees, 3.5 km south-east of the aerodrome. The first responders arrived at the accident site at about 0530. The pilot had not survived.

Shortly after takeoff from Johannesburg-Oliver Reginald Tambo Airport, while climbing, the twin engine aircraft went out of control and crashed near Boksburg, about 5 km south of the airport. Both occupants were killed.

En route from Bangui to Koumbala, province of Bamingui-Bangoran, while cruising at an altitude of 7,000 feet, the pilot encountered technical problems with the right engine that was shut down and its propeller feathered. The pilot declared an emergency and elected to divert to Bambari Airport. Thirteen minutes later, the aircraft went out of control and crashed in an isolated area located about 60 km northwest of Bambari Airport. The aircraft was destroyed by impact forces and a post crash fire and all 10 occupants were killed.

The aircraft impacted mountainous terrain in controlled flight during hours of darkness and marginal VFR conditions. The flight was being vectored for an instrument approach during the pilot's 14 CFR Part 135 instrument competency check flight. The flight was instructed by approach control to maintain VFR conditions, and was assigned a heading and altitude to fly which caused the aircraft to fly into another airspace sector below the minimum vectoring altitude (MVA). FAA Order 7110.65, Section 5-6-1, requires that if a VFR aircraft is assigned both a heading and altitude simultaneously, the altitude must be at or above the MVA. The controller did not issue a safety alert, and in an interview, said he was not concerned when the flight approached an area of higher minimum vectoring altitudes (MVA's) because the flight was VFR and 'pilots fly VFR below the MVA every day.' At the time of the accident, the controller was working six arrival sectors and experienced a surge of arriving aircraft. The approach control facility supervisor was monitoring the controller and did not detect and correct the vector below the MVA.

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.