Recently Released TSB Reports

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The following summaries are extracted from Final Reports issued by the Transportation Safety Board of Canada (TSB). They have been de-identified and include only the TSB's synopsis and selected findings. For more information, contact the TSB or visit their their Web site at -Ed.

TSB Final Report A04Q0026- Separation of Main Rotor on Run-up

On March 8, 2004, a Schweizer 269C-1 helicopter with one pilot on board, was undergoing ground tests following a 100-hr inspection and replacement of the main transmission gearbox. After the second test to check for leaks and to measure tail rotor vibration, engine rpm was reduced. At this time, the pilot and ground engineer heard a noise. The noise was heard again on the third test. Engine rpm was reduced, but this time the main transmission gearbox stopped turning suddenly and caused the main rotor to separate from its shaft. The main rotor rose to an altitude of approximately 150 ft above ground level (AGL) and came to rest on the apron of the heliport, about 100 ft from the helicopter. The helicopter remained in place and there were no injuries. The accident occurred at 11:45 Eastern Standard Time (EST).

TSB Final Report A04Q0026— Separation of Main Rotor on Run-up

Findings as to causes and contributing factors

  1. The input quill bearing housing was not positioned in accordance with the procedures described by the manufacturer; therefore, the flow of oil was obstructed, causing the catastrophic failure of the input quill bearings.
  2. Independent inspection did not detect the incorrect reassembly of the main transmission gearbox.

Other findings

  1. There are no mechanical means to prevent an installation error when installing the input quill bearing housing.
  2. The force required to shear the main rotor shaft is higher than the force required to shear the six rotor head attachment bolts. As a result, the rotor could separate from the shaft in the event of a sudden stoppage of the transmission, which constitutes a hazard for helicopter occupants and people on the ground.

Safety action taken

At the completion of the main transmission overhauls, at sudden stoppage inspections, or in any other situations in which the retainer has to be removed, the overhaul company will paint a red witness line on the retainer and on the transmission housing to assure alignment of oil ports. Also, they will run the transmission for 15 min to check that there is oil flow in the transmission, and to check for oil leaks at the seal and split line. These changes will be put into their worksheets.

TSB Final Report A04Q0026— Separation of Main Rotor on Run-up
Main rotor lies on the ground, after it separated from the aircraft

TSB Final Report A04Q0049- Runway Excursion

On April 19, 2004, a Beechcraft A100 was on a chartered IFR flight from Québec/Jean Lesage International Airport, Que., to Chibougamau/Chapais Airport, Que., with two pilots and three passengers on board. The co-pilot was at the controls and was flying a non-precision approach for Runway 05. The pilot-in-command took the controls less than 1 mi. from the runway threshold and saw the runway when they were over the threshold. At approximately 10:18 Eastern Daylight Time (EDT), the wheels touched down approximately 1 500 ft from the end of Runway 05. The pilot-in-command realized that the remaining landing distance was insufficient. He told the co-pilot to retract the flaps, and applied full power, but did not reveal his intentions. The co-pilot cut power, deployed the thrust reversers, and applied full braking. The aircraft continued rolling through the runway end, sank into the gravel and snow, and stopped abruptly about 500 ft past the runway end. The aircraft was severely damaged. None of the occupants was injured.

TSB Final Report A04Q0049— Runway Excursion

Findings as to causes and contributing factors

  1. The aircraft was positioned over the runway threshold at an altitude that did not allow a landing at the beginning of the runway, and this, combined with a tailwind component and the wet runway surface, resulted in a runway excursion.
  2. Failure to follow standard operating procedures (SOP) and a lack of crew coordination contributed to confusion on landing, which prevented the crew from aborting the landing and executing a missed approach.
  3. The pilot-in-command held several management positions within the company and controlled the pilot hiring and dismissal policies. This situation, combined with the level of experience of the co-pilot compared with that of the pilot-in-command, had an impact on crew cohesiveness.

Findings as to risk

  1. The pilot-in-command decided to execute an approach for Runway 05 without first ensuring that there would be no possible risk of collision with the other aircraft (another Beechcraft 100, inbound from the west).
  2. The regulatory requirement to conform to or avoid the traffic pattern formed by other aircraft is not explicit as to how the traffic pattern should be avoided in terms of either altitude or distance, which can result in risks of collision.
  3. The regulations do not indicate whether the missed approach segment should be considered part of the traffic pattern; this situation can lead pilots operating in uncontrolled airspace to believe that they are avoiding another aircraft executing an instrument approach, when in reality a risk of collision exists.

TSB Final Report A04O0103-Aircraft Stall During Instrument Approach

On April 22, 2004, a Raytheon B300 (Super King Air) aircraft was on a repositioning flight from Earlton, Ont., to Timmins, Ont., with only the flight crew and an engineer on board. At approximately 06:50 EDT, the flight crew was conducting an instrument landing system (ILS) approach to Runway 03 at Timmins. The autopilot was on, and had been in use for the entire flight.

The aircraft was in instrument meteorological conditions (IMC) and icing conditions were encountered. The de-icing boots were being cycled and other anti-icing equipment had been selected ON. The aircraft was in level flight at 2 700 ft above sea level (ASL) in the vicinity of the final approach fix (FAF), with the landing gear down and flaps selected to the approach setting. The aircraft was above the glide slope and the airspeed was approximately 100 knots indicated airspeed (KIAS). The normal approach speed is approximately 125 KIAS. The pilot flying (PF) began to take corrective action just as the aircraft stalled. The PF initiated a stall recovery by applying maximum power and lowering the aircraft's nose. Approximately 850 ft was lost during the stall, and the aircraft reached a minimum height of approximately 800 ft AGL. Once the aircraft recovered from the stall, the crew flew a missed approach. The crew conducted another ILS approach at an approach airspeed of approximately 140 KIAS and landed without further incident. After landing, the flight crew noted 1 to 1½ in. of ice on the aircraft's winglets and static wicks, and some ice on the engine nacelles and fuselage.

Findings as to causes and contributing factors

  1. During the approach, the flight crew did not monitor the airspeed, and it decreased until the aircraft stalled.
  2. The aircraft stalled at a higher-than-normal airspeed for the configuration because it had accumulated ice on critical flying surfaces during the approach.
  3. The aircraft stall warning system did not activate because it was not designed to account for the aerodynamic degradation from the ice accumulation, or to adjust its warning to compensate for the reduced stall angle of attack caused by the ice.
  4. During the approach, the autopilot was not changed from the altitude-hold mode to the approach mode; therefore, the aircraft did not intercept the glide slope. As a result, when the PF decreased the engine power in anticipation of glide slope interception, the aircraft decelerated in level flight.
  5. Because the aircraft was on autopilot, the flight crew members did not notice any indications of impending stall, nor did they notice any signs of decreasing airspeed, such as increasing nose-up attitude, trim changes, increasing angle of attack, and less responsive controls.
  6. The flight crew did not consider that the 140-kt minimum airspeed in sustained icing conditions applied to all phases of flight, including the approach. The crew, therefore, planned to fly the approach at a normal approach airspeed of 125 KIAS.
  7. Because the flight crew members did not characterize the icing conditions as severe, they did not follow the precautions specified in the aircraft flight manual (AFM) for flight in severe icing conditions, such as requesting priority handling from ATC to exit the icing conditions, or disengaging the autopilot.
  8. The flight crew did not practise effective crew resource management (CRM) during the approach: there was no discussion of appropriate procedures for conducting the approach in icing conditions, and critical flight parameters were not effectively monitored by either crew member.

Findings as to risk

  1. Other than the CRM training both flight crew members received during their aircraft-type training at Flight Safety International (FSI), neither pilot had any recent, formal CRM training. Since the flight was conducted under Canadian Aviation Regulation (CAR) 604, specific CRM training was not required, nor is it required for CAR 704 operations.
  2. The first officer, who was the pilot not flying (PNF), had no specific training in the role and duties of the PNF during his initial type training at FSI, and there is no
    regulatory requirement to receive this type of training.
  3. Typically, flight crews receive only limited training in stall recognition and recovery, where recovery is initiated at the first indication of a stall. Such training does not allow pilots to become familiar with natural stall symptoms, such as buffet, or allow for practise in recovering from a full aerodynamic stall.
  4. Typically, the training of flight crews for flight in icing conditions is limited to familiarization with anti-icing and de-icing equipment and simulator training, while the opportunity to train for flight in actual icing conditions is limited.
  5. Inappropriate guidance on pneumatic de-ice boot operating procedures can lead to de-ice boots being used in a less-than-optimal manner.
  6. Inconsistent guidance on autopilot use in icing conditions can lead to its use in conditions where hand flying would provide an increased opportunity to recognize an imminent stall.
  7. Typically, aircraft such as the Raytheon B300 are not equipped with a low airspeed alerting system.

TSB Final Report A04P0142-In-flight Power Loss

On April 28, 2004, a Bell 206L helicopter was in cruise flight at an altitude of about 700 ft ASL when the pilot heard a sudden unusual noise, and subsequently experienced an engine power loss. He lowered the collective and checked the instruments while scanning the area for a landing spot. The engine was still running; however, the turbine outlet temperature was climbing very rapidly and quickly exceeded the range of the gauge. The pilot subsequently raised the collective slowly, but the main rotor started to droop. He advised the two passengers of an engine failure and entered auto-rotation. While initiating a flared landing, he pulled the collective and confirmed no power from the engine as the low rotor horn sounded. The helicopter landed on a logging road near Tasu Creek, Queen Charlotte Islands, B.C., in the Sandspit area at 08:29 Pacific Daylight Time (PDT). The pilot shut down the engine immediately on landing. There were no injuries or airframe damage.

Arrow pointing to blade failure caused by thermally-induced fatigue cracking

Arrow pointing to blade failure caused by thermally-induced fatigue cracking

Finding as to causes and contributing factors

  1. Thermally-induced fatigue cracking initiated radially inward in a low-cycle mode in the blade platform fillet area, then progressed normal to the blade axis in a high-cycle mode, eventually resulting in a blade failure due to overstress rupture when the remaining area could no longer support the applied loads.

Findings as to risk

  1. Hot starting events and/or power transients are not recorded in this type of helicopter and may not be recorded accurately by an operator even if detected. Turbine wheel failures may occur when hot starts and power transients are undetected, or if their effects go unchecked.
  2. The first-stage turbine wheel revealed many type A, and approximately four type B, cracks in the blade rim, and cracks in the fillet radius of blades can lead to turbine failures. There is no prescribed scheduled inspection to detect these cracks, but a turbine special inspection is recommended when turbine outlet temperature limits are exceeded. No cracks in the blades are allowed.

Other finding

  1. Approximately 25 percent of the major diameter seal was missing from the rear support as a result of disbonding due to a bond failure that likely resulted in a slight loss of engine efficiency.

TSB Final Report A04A0148-Collision with Terrain

On December 5, 2004, a Piper PA-28-140 with an instructor-pilot and student on board, departed St. John's International Airport, N.L., at 13:38 Newfoundland Standard Time (NST) for a local instructional flight. The aircraft climbed on a southwesterly heading to 2 000 ft ASL. At 13:43, the pilot reported leaving the control zone, which was the last radio communication from the aircraft.

ATC radar data showed that the aircraft then descended gradually while executing a series of 90º turns. The aircraft's ground speed during the descent was between 50 and 70 kt (all radar speeds are ± 5 kt). After the fourth turn, the aircraft's ground speed increased to 100 kt. The aircraft then disappeared from radar at about 600 ft ASL (200 ft AGL), reappearing 37 seconds later at 700 ft ASL (about 250 ft AGL) (all radar altitudes are ± 50 ft). The aircraft entered a tight left turn then disappeared finally from radar at 13:52:10, while on a westerly heading at 70 kt ground speed. The position of the last radar return coincided with the location of the accident site. The student pilot died in the crash. The instructor received serious injuries, including head injuries with post-trauma amnesia, and was not able to provide investigators with information relating to the accident. Shortly after the accident, occupants of a passing vehicle noticed the aircraft wreckage and called 9-1-1 at 13:59:51. There were no known witnesses to the accident.

TSB aircraft accident investigator Allan Chaulk examines the wreckage

TSB aircraft accident investigator Allan Chaulk examines the wreckage

Findings as to causes and contributing factors

  1. The aircraft was flying in conditions conducive to serious carburetor icing at any engine power setting. It is likely that carburetor ice formed and restricted the engine power available to the point where the aircraft would not maintain level flight.
  2. The aircraft subsequently struck the ground, perhaps as the result of a stall.

TSB Final Report A04Q0199-Runway Excursion

On December 24, 2004, a Beech King Air BE-A100 departed Puvirnituq, Que., under IFR for a scheduled flight to Kuujjuaq, Que. There were two crew members, four passengers, and cargo on board. Strong crosswinds and slippery runway surface conditions had been reported by the Kuujjuaq flight service station (FSS) personnel. The crew conducted an ILS approach to Runway 07 in IMC and touched down at 19:43 EST. Immediately after landing, the aircraft started skidding to the right and departed the landing surface, coming to a rest 1 600 ft from the threshold, and 40 ft to the right of the runway. The aircraft was substantially damaged, but none of the crew or passengers was injured.

TSB Final Report A04Q0199—Runway Excursion

Findings as to causes and contributing factors

  1. The crew did not assimilate the information regarding wind and runway conditions, and continued an approach for which there was no viable landing option.
  2. The first officer did not anticipate a landing on Runway 07, which did not allow the crew to properly discuss the risk of landing on a slippery runway in strong crosswind conditions.
  3. The flight crew did not make use of crosswind charts during flight planning or when preparing to land at Kuujjuaq.
  4. Company SOPs do not provide specific guidance with respect to maximum crosswind or minimum Canadian Runway Friction Index (CRFI) values.

Other finding

  1. It is possible that the crew may have felt some degree of self-induced pressure to land at Kuujjuaq, given that it was Christmas Eve, and that cargo consisted mainly of company Christmas presents.

Safety action taken

The operator has released a crosswind limits SOP bulletin that indicates a crosswind limit for the aircraft, and emphasizes the need to make reference to the prevailing runway surface conditions for both the planning and in- flight phases of the flight.

TSB Final Report A05P0038-Dual Engine Power Loss and Hard Landing

On February 24, 2005, the pilot of a Bell 212 helicopter was carrying out heli-skiing operations in the Blue River area of British Columbia. After taking off from the top of a glacier, at about 8 000 ft ASL, the pilot made a downwind approach to land at a pick-up area at the toe of another glacier. When the helicopter was at about 150 ft AGL, and at about 30 kt air speed, the pilot increased the collective pitch to slow his rate of descent, but the engines (Pratt & Whitney Canada PT6T-3DF) did not respond. The low rotor rpm warning sounded and the rotor rpm decreased. The pilot lowered the collective and confirmed that the rpm beep was full up and the engine throttles were fully open.

The pilot flew the helicopter toward a snow-covered, frozen lake. The sink rate could not be arrested as the rotor rpm had not recovered, and the helicopter landed hard, yawed right about 90º and remained upright. The deep snow absorbed some of the impact forces, but the helicopter was substantially damaged. After the landing, the rotor rpm appeared to start accelerating and the pilot shut the engines down immediately. The pilot, the only person on board, was not injured.

Findings as to causes and contributing factors

  1. The installation of a non-standard torque control unit (TCU) required that the engine Nf governors be rigged abnormally. The non-approved rigging amplified the effect of normal-type wear in the governors; the governors did not function properly, resulting in inadequate power from both engines upon pilot demand.
  2. Rpm and torque oscillations probably aggravated the opposing engine rpm governors' weaknesses due to wear, and caused malfunctions at the same time.
  3. The loss of power in both engines occurred at a critical time of flight, resulting in a hard landing.

Finding as to risk

  1. In-service wear causes the governors to malfunction before reaching their overhaul life of 4 500 hr; the average time in service before they are removed for repair is about 1 600 hr.

TSB Final Report A05P0262-Helicopter Roll-over-Glassy Water

On October 26, 2005, a Bell 206B helicopter, equipped with fixed float landing gear, was carrying out lake watersampling operations for Environment Canada. It departed Chilliwack, B.C., with one pilot and two Environment Canada employees on board. Their mission involved landing on lakes north of the Vancouver Lower Mainland area to collect water samples. Following landings on eight different lakes, where the winds were light and variable, they attempted to land on Devils Lake, where the wind was calm. The water was quite glassy and was shaded from the sun by hills. The pilot made a shallow approach from the south to the middle of the lake, with reference to the shoreline 200 to 400 m away and some small ripples on the water. Before the pilot anticipated touching down, the helicopter struck the surface of the lake and flipped onto its back. It remained afloat supported by the floats, but the cabin was submerged. The passenger from the back seat and the pilot were able to exit the wreckage, but the passenger seated in the left front seat was unconscious. The passenger who had escaped the wreckage rescued the front-seat passenger but she died about six days later from injuries received in the accident. The helicopter sustained substantial damage. The accident occurred at about 13:00 PDT.

TSB Final Report A05P0262—Helicopter Roll-over—Glassy Water

Findings as to causes and contributing factors

  1. Glassy water conditions impaired the pilot's ability to judge his height above the lake, and during the landing, the helicopter's floats contacted the water before the pilot expected them to, dug in, and the helicopter flipped over.
  2. One of the helicopter's main-rotor blades broke on contact with the water and penetrated the front of the helicopter. Wreckage debris struck the pilot and the front-seat passenger on their heads.

Other findings

  1. The pilot was wearing a helmet, which protected him from serious head injuries.
  2. Recent underwater emergency escape training contributed to one passenger's ability to safely escape from the helicopter and rescue the other passenger from the submerged wreckage.
  3. A satellite telephone was available; this contributed to prompt accident scene response.

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