Country
Crash of a De Havilland DHC-6 Twin Otter 100 off Vancouver
Date & Time:
Nov 1, 2000 at 1510 LT
Operator:
Registration:
C-GGAW
Survivors:
Yes
Schedule:
Vancouver - Victoria
MSN:
086
YOM:
1967
Flight number:
8O151
Crew on board:
2
Crew fatalities:
Pax on board:
15
Pax fatalities:
Other fatalities:
Total fatalities:
0
Captain / Total hours on type:
2500.00
Copilot / Total hours on type:
1650
Circumstances:
A de Havilland DHC-6-100 float-equipped Twin Otter (serial number 086), operated by West Coast Air Ltd., was on a regularly scheduled flight as Coast 608 from Vancouver Harbour water aerodrome, British Columbia, to Victoria Harbour water aerodrome. The flight departed at about 1510 Pacific standard time with two crew members and 15 passengers on board. Shortly after lift-off, there was a loud bang and a noise similar to gravel hitting the aircraft. Simultaneously, a flame emanated from the forward section of the No. 2 (right-hand) engine, and this engine completely lost propulsion. The aircraft altitude was estimated to be between 50 and 100 feet at the time. The aircraft struck the water about 25 seconds later in a nose-down, right wing-low attitude. The right-hand float and wing both detached from the fuselage at impact. The aircraft remained upright and partially submerged while the occupants evacuated the cabin through the main entrance door and the two pilot doors. They then congregated on top of the left wing and fuselage. Within minutes, several vessels, including a public transit SeaBus, arrived at the scene. The SeaBus deployed an inflatable raft for the occupants, and they were taken ashore by several vessels and transported to hospital for observation. There were no serious injuries. The aircraft subsequently sank. All of the wreckage was recovered within five days.
Probable cause:
Findings as to Causes and Contributing Factors:
1. A planetary gear disintegrated in the propeller reduction gearbox of the No. 2 engine and caused the engine drive shaft to disconnect from the propeller, resulting in a loss of propulsion from this engine.
2. The planetary gear oil strainer screen wires fractured by fatigue as a consequence of the installation at the last overhaul. This created an unsafe condition and it is most probable that the release of wire fragments and debris from this strainer screen subsequently initiated or contributed to distress of the planetary gear bearing sleeve and resulted in the disintegration of the planetary gear.
3. Although airspeed was above Vmc at the time of the power loss, the aircraft became progressively uncontrollable due to power on the remaining engine not being reduced to relieve the asymmetric thrust condition until impact was imminent.
Findings as to Risk:
1. The propeller reduction gearboxes were inspected in accordance with the West Coast Air maintenance control manual. These inspections exceeded requirements of the de Havilland Equalized Maintenance Maximum Availability program. Since the last inspection, 46 hours of flight time before the accident, did not reveal any anomaly, a risk remains of adverse developments with
resulting consequences occurring during the unmonitored period between inspections.
2. Regulations require the installation of engine oil chip detectors, but not the associated annunciator system on the DHC-6. Without an annunciator system, monitoring of engine oil contamination is limited to the frequency and thoroughness of maintenance inspections. An annunciator system would have provided a method of continuous monitoring and may have warned the crew of the impending problem.
3. Although regulations do not require the aircraft to be equipped with an auto-feather system, its presence may have assisted the flight crew in handling the sudden loss of power by reducing the drag created by a windmilling propeller.
4. Since most air taxi and commuter operators use their own aircraft rather than a simulator for pilot proficiency training, higher-risk emergency scenarios can only be practiced at altitude and discussed in the classroom. As a result, pilots do not gain the benefit of a realistic experience during training.
Other Findings:
1. The fact that the aircraft remained upright and floating in daylight conditions contributed to the successful evacuation of the cabin without injury and enabled about half of the passengers to locate and don their life vests.
2. The aircraft was at low altitude and low airspeed at the time of power loss. The selection of full flaps may have contributed to a single-engine, high-drag situation, making a successful landing difficult.
1. A planetary gear disintegrated in the propeller reduction gearbox of the No. 2 engine and caused the engine drive shaft to disconnect from the propeller, resulting in a loss of propulsion from this engine.
2. The planetary gear oil strainer screen wires fractured by fatigue as a consequence of the installation at the last overhaul. This created an unsafe condition and it is most probable that the release of wire fragments and debris from this strainer screen subsequently initiated or contributed to distress of the planetary gear bearing sleeve and resulted in the disintegration of the planetary gear.
3. Although airspeed was above Vmc at the time of the power loss, the aircraft became progressively uncontrollable due to power on the remaining engine not being reduced to relieve the asymmetric thrust condition until impact was imminent.
Findings as to Risk:
1. The propeller reduction gearboxes were inspected in accordance with the West Coast Air maintenance control manual. These inspections exceeded requirements of the de Havilland Equalized Maintenance Maximum Availability program. Since the last inspection, 46 hours of flight time before the accident, did not reveal any anomaly, a risk remains of adverse developments with
resulting consequences occurring during the unmonitored period between inspections.
2. Regulations require the installation of engine oil chip detectors, but not the associated annunciator system on the DHC-6. Without an annunciator system, monitoring of engine oil contamination is limited to the frequency and thoroughness of maintenance inspections. An annunciator system would have provided a method of continuous monitoring and may have warned the crew of the impending problem.
3. Although regulations do not require the aircraft to be equipped with an auto-feather system, its presence may have assisted the flight crew in handling the sudden loss of power by reducing the drag created by a windmilling propeller.
4. Since most air taxi and commuter operators use their own aircraft rather than a simulator for pilot proficiency training, higher-risk emergency scenarios can only be practiced at altitude and discussed in the classroom. As a result, pilots do not gain the benefit of a realistic experience during training.
Other Findings:
1. The fact that the aircraft remained upright and floating in daylight conditions contributed to the successful evacuation of the cabin without injury and enabled about half of the passengers to locate and don their life vests.
2. The aircraft was at low altitude and low airspeed at the time of power loss. The selection of full flaps may have contributed to a single-engine, high-drag situation, making a successful landing difficult.
Final Report:
Crash of a De Havilland DHC-6 Twin Otter 200 in Raleigh: 1 killed
Date & Time:
Jul 31, 2000 at 0034 LT
Operator:
Registration:
N201RH
Survivors:
Yes
Schedule:
Hinckley - Louisburg
MSN:
163
YOM:
1968
Crew on board:
1
Crew fatalities:
Pax on board:
2
Pax fatalities:
Other fatalities:
Total fatalities:
1
Captain / Total hours on type:
147.00
Aircraft flight hours:
28711
Circumstances:
The flight had proceeded without incident until a visual approach was made to the destination airport, but a landing was not completed because of poor visibility due to ground fog. The pilot then requested vectors to another airport, and was advised by ATC that he was below radar coverage, and he could not be radar identified. The pilot stated he would proceed to a third airport; he was given a heading, instructed to proceed direct to the airport, and report the field in sight. He was told to over-fly the airport, and might be able to descend through a clearing in the clouds. An inbound air carrier flight reported instrument meteorological conditions on the final approach to a parallel runway. At a location of 1.13 miles east of the airport, the flight, for no apparent reason, turned south, away from the airport. The last radio contact with pilot was after ATC told him his heading was taking him away from the airport and he said he was turning back. The last known position of N201RH was 1.95 miles southeast of the airport, at 500 feet MSL. According to the statement of the passenger that was sitting in the co-pilot's seat, "...all we could see were city lights and darkness underneath us. We were in a right turn, when I saw the trees and subsequently hit it." According to the pilot's log book and FAA records revealed a limitation on his commercial pilot certificate prohibited him from carrying passengers for hire at night and on cross-country flights of more than 50 nautical miles. The records did not show any instrument rating. As per the entries in his personal flight logbook, he had accumulated a total of 1,725.2 total flight hours, 1,550.9 total single engine flight hours, and 184.3 total flight hours in multi-engine aircraft of which 145.6 hours were in this make and model airplane. In addition, the logbooks showed that he had a total of 487.3 cross country flight hours, 61.9 total night flight hours, and 21.6 simulated instrument flight hours.
Probable cause:
The pilot's continued VFR flight into IMC conditions, by failing to maintain altitude, and descending from VFR conditions into IMC, which resulted in him subsequently impacting with trees. Factors in this accident were: reduced visibility due to dark night and fog. An additional factor was the pilot was not certified for instrument flight.
Final Report:
Crash of a De Havilland DHC-6 Twin Otter 300 near Dhangadhi: 25 killed
Date & Time:
Jul 27, 2000 at 1035 LT
Operator:
Registration:
9N-ABP
Survivors:
No
Schedule:
Bajhang - Dhangadhi
MSN:
654
YOM:
1979
Crew on board:
3
Crew fatalities:
Pax on board:
22
Pax fatalities:
Other fatalities:
Total fatalities:
25
Circumstances:
While descending to Dhangadhi Airport, the crew encountered marginal weather conditions and limited visibility due to low clouds. At an altitude of 4,300 feet, the aircraft struck the slope of Mt Jarayakhali located 29 km from Dhangadhi Airport runway 09. The aircraft was destroyed by impact forces and a post crash fire and all 25 occupants were killed.
Probable cause:
Controlled flight into terrain.
Crash of a De Havilland DHC-6 Twin Otter 300 in Carreto: 10 killed
Date & Time:
Mar 17, 2000 at 0930 LT
Operator:
Registration:
HP-1267APP
Survivors:
No
Schedule:
Panama City - Puerto Obaldía
MSN:
624
YOM:
1979
Crew on board:
2
Crew fatalities:
Pax on board:
8
Pax fatalities:
Other fatalities:
Total fatalities:
10
Circumstances:
While descending at an altitude of 7,500 feet in relative good weather conditions, the crew informed ATC about their position when contact was lost. The wreckage was found five days later at the altitude of 762 metres on the slope of a mountain (850 metres high) located near Carreto, about 22 km northwest pf Puerto Obaldía Airport. All 10 occupants were killed. The crew was descending under VFR mode when the accident occurred for unknown reasons.
Crash of a De Havilland DHC-6 Twin Otter 300 in Simara: 10 killed
Date & Time:
Dec 25, 1999 at 1502 LT
Operator:
Registration:
9N-AFL
Survivors:
No
Schedule:
Simara - Kathmandu
MSN:
796
YOM:
1982
Crew on board:
3
Crew fatalities:
Pax on board:
7
Pax fatalities:
Other fatalities:
Total fatalities:
10
Circumstances:
The twin engine aircraft departed Simara Airport at 1457LT on a schedule flight to Kathmandu with 10 people on board. Three minutes after takeoff, while climbing in marginal weather conditions, the aircraft struck the slope of Mt Burja Lek located few km from the airport. The aircraft disintegrated on impact and all 10 occupants were killed. At the time of the accident, the visibility was estimated to be 5 km with low ceiling.
Probable cause:
Controlled flight into terrain after the crew failed to follow the correct route after takeoff and continued at an insufficient altitude until the aircraft collided with terrain.
