Recently Released TSB Reports

Rapports du BST publiés réremment

The following summaries are extracted from Final Reports issued by the Transportation Safety Board of Canada (TSB). They have been de-identified and include the TSB’s synopsis and selected findings. Some excerpts from the analysis section may be included, where needed, to better understand the findings. We encourage our readers to read the complete reports on the TSB Web site. For more information, contact the TSB or visit their Web site at www.tsb.gc.ca. —Ed.

TSB Final Report A06O0186—Collision with Terrain

On July 19, 2006, an American-registered float-equipped Cessna 180H took off from Cordingley Lake, Ont., at 09:05 Eastern Daylight Time (EDT) on a local flight with the pilot and two passengers on board. The owner of the aircraft, a licensed pilot, occupied the right rear seat, and a second passenger—also a licensed pilot—was in the right front seat. After completing the engine run-up checks, the take-off run was commenced without backtracking. After liftoff, the aircraft reached tree-top height but would not continue to climb or accelerate. As the aircraft crossed the shoreline and made initial contact with the tops of trees, full flaps were selected and the aircraft nose was raised so that the floats would absorb the impact. The floats struck the trees and the aircraft pitched nose-down and struck the ground in a near-vertical attitude. The three occupants received minor injuries. A small, post-impact, fuel-fed fire occurred forward of the firewall; the fire did not spread beyond that localized area.

Aircraft take-off path
Aircraft take-off path

Findings as to causes and contributing factors

  1. In approving the supplemental type certificate (STC) for the three-blade propeller, the U.S. Federal Aviation Administration (FAA) did not recognize that the performance analysis provided by the applicant was not valid for the floatplane version or that there would be an associated performance reduction.
  2. As a result of the performance reduction, the aircraft could not achieve the published take-off and climb performance specifications; this contributed to its inability to clear the obstacles at the end of the lake.
  3. The pilot was not familiar with the take-off procedure developed by the owner of the aircraft to compensate for the performance degradation.
  4. During the takeoff, the owner occupied a rear seat where he could not adequately monitor the takeoff and provide appropriate advice to the pilot.
  5. The pilot did not use the full length of the lake for takeoff, reducing the time available to assess the aircraft’s performance and limiting the options available when the expected performance was not achieved.

Findings as to risk

  1. Maintaining full power after the aircraft was committed to descending into the trees increased the risk of damage and post-impact fire.
  2. The type certificate data sheet for the Cessna 180 indicates that a wide variety of propellers may be installed on the aircraft, but does not define which propellers are approved only for the landplane and, therefore, are not suitable for the floatplane. As a result, maintenance organizations and aircraft owners may unknowingly install propellers that do not satisfy the airworthiness standards for the aircraft.
  3. The 1969 Cessna 180 floatplane, amphibian, and skiplane owner’s manual supplement does not indicate either in the limitations section or the required equipment section that the airworthiness standards for the aircraft require that an 88-in. propeller be installed. As a result, pilots and operators will be unaware that shorter-diameter propellers are not approved for use on the floatplane version of the aircraft.
  4. STC SA1749WE, for the installation of Canadian aircraft products series 3000D floats, approves the floats for operation at higher gross weight than the floats they replace, but does not provide performance operating data at the higher gross weight.

Safety action taken
Hartzell Propeller Inc. is studying the effect on aircraft performance of the propellers listed on the Cessna 180 type certificate data sheets. If flight tests are required, it will present the results to the FAA. It will also keep the TSB advised of its test progress and discussions with the FAA.

TSB Final Report A06A0115—Loss of Cabin Pressure

On November 3, 2006, a Canadair CL600-2B19 was on a scheduled flight from Toronto, Ont., to Fredericton, N.B. While in cruise at FL330, the flight crew observed the cabin altitude climbing at a rate of approximately 1 000 ft/min. A descent clearance to FL250 was requested from the Moncton area control centre (ACC) and, after the aircraft was level at FL250, a continued increase in cabin altitude was observed. The crew requested and received clearance for further descent to 9 000 ft. The pilots donned their oxygen masks during the descent as the cabin altitude climbed through 10 000 ft. When the cabin altitude reached 14 000 ft, the passenger oxygen masks automatically deployed. The aircraft was levelled at 9 000 ft where it remained until descent for final approach was initiated. The aircraft landed at Fredericton without further incident at 2115 Co-ordinated Universal Time (UTC). There were no injuries to the 50 passengers or 3 crew members.

Finding as to causes and contributing factors

  1. The combined effect of the detached left air conditioning unit pack system air supply duct, the detached right system pressure regulating shut-off valve line, and the missing return spring on the left system bulkhead check valve resulted in the loss of cabin pressurization.

TSB Final Report A06A0114—Collision with Obstacle During Takeoff

On November 6, 2006, a de Havilland DHC-6-300 Twin Otter had been converted from float to wheel landing gear and was being repositioned from the Marine Atlantic dock to the Goose Bay, N.L., airport. During the takeoff from the dock, the main wheels of the aircraft struck a wooden safety curb that surrounded the dock perimeter. After visually inspecting the landing gear in flight, the pilots continued the planned flight and landed at the Goose Bay airport. On landing, the right main gear collapsed and separated from the aircraft. The aircraft veered to the right and came to rest on a taxiway on the right side of the runway. There was damage to the right landing gear, the right wing tip, and the outboard aileron hinge. There were no injuries to the two pilots on board. The accident occurred at 16:31 Atlantic Standard Time (AST), during daylight hours.

Photograph of accident area

Analysis
There is a history of DHC-6 operators successfully conducting takeoffs from the marine dock after float-to-wheel conversions. Although this was the first attempt by this captain to take off from the dock, the first officer had completed a number of takeoffs from the dock with another operator. Both pilots were highly experienced on type, and both mentally calculated that there was sufficient distance on the planned take-off path to get airborne safely. However, the take-off distance available measurement was shorter than estimated, and the reduction in take-off performance due to the effect of the dock depression was unforeseen. The combination of these circumstances resulted in the landing gear striking the wooden safety curb.

The aircraft was being operated under Canadian Aviation Regulation (CAR) 704 and the associated requirements of the company operations manual (COM). However, not all of these requirements were met in that the discussion between the captain and the director of flight operations (DFO) or chief pilot did not take place. This discussion might have led to an alternative course of action to mitigate the risks associated with taking off from the dock.

Findings as to causes and contributing factors

  1. The take-off length available on the dock was shorter than estimated. This, in combination with the reduction in take-off performance due to the effect of the dock depression, resulted in the landing gear striking the wooden safety curb.
  2. The right main landing gear collapsed on landing as a result of damage incurred when the gear struck the wooden safety curb.

Findings as to risk

  1. The COM’s required discussion between the captain and the DFO or chief pilot did not take place. This discussion might have led to an alternative course of action to mitigate the risks associated with taking off from the dock.
  2. The cockpit voice recorder (CVR) was not operating because of a faulty inertia switch. In a more serious accident, crucial investigation data and safety information could have been lost.
  3. Failure of Technical Standard Order (TSO) C91-compliant Pointer emergency locator transmitter (ELT) mounting brackets (part number 2017) in an accident could cause a malfunction of the transmitter and prevent a timely and effective search and rescue response.

Other finding

  1. If the actual take-off distance available had been what the captain had estimated (400 ft), the takeoff would likely have been successful.

Safety action taken
As a result of this accident, the operator has taken the following actions: ceased take-off operations from the dock; submitted a service difficulty report (SDR) on the faulty CVR inertial switch to Transport Canada; and removed the clip-type ELT mounting bracket and replaced it with the mounting bracket with the hold-down strap.

TSB Final Report A07C0082—Loss of Control—Collision with Terrain

On May 17, 2007, a float-equipped Cessna 180J was en route from Miller Lake, Ont., to Roderick Lake, Ont., returning from a series of camp re-supply and maintenance flights. The aircraft was reported as missing at 21:30 Central Daylight Time (CDT) when it did not arrive at Roderick Lake. Search and rescue personnel discovered the wreckage in a wooded area near the shoreline of Miller Lake. The pilot had sustained fatal injuries. The single passenger was trapped in the wreckage and had sustained serious injuries. The aircraft was substantially damaged.

Photograph of accident area

Analysis
Damage to the aircraft was consistent with an impact with the ground after a low-level wing stall. The aircraft’s exact flight path could not be determined. However, conditions were conducive for low-level wind shear at the time of the accident, and the aircraft was configured for takeoff or manoeuvring flight. A possible accident scenario is that the aircraft encountered wind shear while manoeuvring in the vicinity of the operator’s boat cache north of Miller Lake, resulting in a stall at an altitude from which the pilot could not recover.

The accident occurred at approximately 14:30 CDT. However, the aircraft was not reported as missing until 21:30 CDT because it was not expected to arrive at Roderick Lake until 20:00 CDT. Consequently, the flight watch system used by the camp operator and pilot delayed initiation of the search and rescue mission by seven hours. The late start, deteriorating weather, and the absence of an emergency locator transmitter (ELT) signal all contributed to a lengthy rescue mission, which extended the time that the passenger was trapped in the wreckage to approximately 18 hr.

Finding as to causes and contributing factors

  1. The aircraft stalled while manoeuvring at an altitude from which recovery was not possible. The stall was most likely induced by low-level wind shear.

Findings as to risk

  1. The company’s flight watch system delayed the initiation of the search and rescue response.
  2. The ELT had been turned off and was out of reach of the trapped passenger. The absence of an ELT signal compounded the difficulty in locating the aircraft and extended the duration of the search.

Safety action taken
After the accident, the operator purchased an aircraft satellite tracking system for its aircraft.

The operator implemented a procedure whereby a satellite telephone is carried on all camp maintenance flights and pilots are required to report flight-following information to the operator’s dispatch personnel.

TSB Final Report A07A0056—Reduction Gearbox Failure

On June 3, 2007, a Bell 407 helicopter was en route to Postville, N.L., from the Jacques Lake drilling site, with the pilot as the sole occupant and an empty fuel tank weighing approximately 450 lbs on a 75-ft longline. At 500 ft above ground level (AGL), the engine chip light illuminated along with audible indications of an engine failure. Immediately after, there were two indications on the full authority digital engine control (FADEC): FADEC Fail and FADEC Degrade, followed by the audible engine-failure horn. Engine power output degraded and the pilot entered autorotation. At approximately 200 ft AGL, the pilot released the longline, landed in a bog, and exited the helicopter uninjured. The aircraft was undamaged, and there was minimal environmental impact. The incident occurred at 09:00 Atlantic Daylight Time (ADT).

Broken torquemeter gear
Broken torquemeter gear

Finding as to causes and contributing factors

  1. The helical torquemeter gear failed as a result of an undetected crack that progressed in fatigue. The failure of the torquemeter gear resulted in the loss of engine power to the helicopter’s transmission.

Findings as to risk

  1. In-service wear may cause torquemeter gear (part number 6893673) to wear prematurely.
  2. Because it is not mandatory to replace torquemeter gear (part number 6893673) with the newly released torquemeter gear, it is possible that torquemeter gear (part number 6893673) will experience premature wear and failure.
  3. The Rolls-Royce 250-C47B Operation and Maintenance Manual inspection requirements allow the torquemeter gear and other gears installed in the gearbox to potentially exceed 3 500 hr in service before a magnetic particle inspection (MPI) is carried out.
  4. The current visual and radius scribe inspections may be inadequate to detect cracks in the gear teeth.
  5. The Rolls-Royce Operation and Maintenance Manual identifies the requirement for an MPI on the torquemeter gear and other gears in the gearbox based on their time in service. However, there is no requirement to track the time in service for any of these parts.

Safety action taken
On August 17, 2007, Rolls-Royce issued Commercial Engine Bulletin (CEB) 72-6061, which advised customers of the 250-C30 and 250-C47 series engines that the power gears (pinion gear, torquemeter gear, and power take-off gear) had been redesigned to improve the reliability of the new gears. The CEB stated that compliance was a customer option.

On March 26, 2008, Rolls-Royce advised that it was developing a visual inspection to be placed into the 2 000-hr inspection section in the Operation and Maintenance Manual. Implementation was targeted for the third quarter of 2008.

On July 11, 2008, Transport Canada issued Service Difficulty Alert AL 2008-01 regarding this issue.

TSB Final Report A07A0096—Engine Failure/Forced Landing

On August 27, 2007, a privately-operated Ayres S-2R spray plane was returning to the Boston Brook, N.B., airstrip after having completed the second spray-application flight of the day. The aircraft was at an altitude between 200 and 300 ft above ground level (AGL), approximately 2 NM from the airstrip, when the engine began to run rough. At approximately 08:13 Atlantic Daylight Time (ADT), the pilot contacted a company maintenance engineer by radio to report the problem. The engine then began to produce smoke and, eventually, it stopped running. A forced landing was carried out into a stand of trees at the edge of a cutover. The aircraft was substantially damaged, but the pilot escaped injury. There was no post-impact fire.

Aircraft’s final position
Aircraft’s final position

Analysis
When the engine began to vibrate, the pilot attempted to identify and rectify the problem. He was not successful as there was very little time from the first indication of engine trouble to when the engine stopped completely. Under these circumstances, the pilot had no choice but to conduct a forced landing. The aircraft had only reached an altitude of approximately 200 to 300 ft AGL following completion of the spray task when the engine began to run rough. This left the pilot with little time to prepare for the forced approach or to select a more suitable landing area.

Examination of the engine showed that it contained sufficient lubricating oil and that the oil filter screens were free of metal particles or other contamination. This indicates that the engine was not making metal prior to the failure. Therefore, the imminent failure would not have been detectable during routine maintenance activity. Oil supply and engine maintenance were not a factor in the failure. The propeller, valve train, and accessory gearbox sections of the engine did not contribute to the engine failure.

The damage to cylinder No. 5 suggests that the associated connecting rod failed first in the sequence. It then penetrated the cylinder sleeve as the engine continued to operate. The failure initiated a chain of overload failures for each of the remaining connecting rods in rapid succession until the engine stopped operating. Due to the severity of damage to the fracture surfaces of connecting rod No. 5, the mode of failure could not be determined.

Findings as to causes and contributing factors

  1. Connecting rod No. 5 failed for undetermined reasons. This failure initiated a sequence that resulted in the overload failure of the remaining connecting rods.
  2. When the engine failed, the pilot had little time to prepare for the forced approach due to the low altitude of the aircraft.

TSB Final Report A07A0118—In-Flight Collision Between Two Helicopters

On October 3, 2007, a Bell 206 Long Ranger was taking off from a fuel-staging area south of Postville, N.L., at 10:00 Atlantic Daylight Time (ADT). At the same time, a Eurocopter AS 350 BA Astar was on approach to land at the same fuel-staging area. The Astar was carrying a sling load on a longline. During departure, the Bell 206L collided with the longline, causing the Bell 206L to break up in flight and crash near the shore of Kaipokok Bay, on the southern edge of Postville. The pilot, the sole occupant on board the Bell 206L, was fatally injured and the helicopter was destroyed. The pilot of the Astar maintained control of the helicopter and landed safely at the Postville airport; he was not injured, but the Astar sustained substantial damage.

Photograph of accident area
Photograph of accident area

Analysis
The key to flight safety in the vicinity of uncontrolled airports is good radio communication and visual alertness. It is highly recommended that aircraft operating within an aerodrome traffic frequency (ATF) area follow the mandatory radio reporting procedures outlined in the Canadian Aviation Regulations (CARs) for operations within a mandatory frequency (MF) area. Use of these procedures is at the discretion of the aircraft operators while operating in an ATF area. Pilots have sole responsibility for seeing and avoiding other aircraft.

No broadcast was heard stating the Bell 206L pilot’s intention to take off from the fuel-staging area. Had the Astar pilot known the Bell 206L was intending to take off, he could have possibly taken action in time to avoid a collision.

While positioned on the ground facing the fuel tanks, the Bell 206L pilot, who was seated on the right side of the aircraft, would have had difficulty seeing the Astar or the sling load approaching from above, behind, and to the left. A hover turn to the left prior to departure would have allowed the pilot to see the Astar and its sling load on approach. The reason for not executing this safety check to confirm that his intended flight path was clear of traffic is not known.

Although the Astar pilot made two position reports, it is probable that these broadcasts were not heard by the Bell 206L pilot. It is possible that the Bell 206L pilot had not yet donned his headset or that he had not yet powered the radios at the time the Astar pilot made his reports. The Astar pilot did not broadcast his aircraft’s position when he was on final approach or on short final to the fuel-staging area. Despite the fact that the Astar pilot saw the Bell 206L rotors turning, and because the Bell 206L pilot had not broadcast his intentions to take off, the Astar pilot assumed he was not ready to take off or that he was shutting down. Also, the fact that the Bell 206L pilot had not responded to the Astar pilot’s position report when he was 3 NM inbound would have indicated to the Astar pilot that the Bell 206L would not be a conflict.

Longline operations require a significant amount of attention from pilots, especially when flying in the vicinity of other objects or close to the ground. On short final, just prior to the collision, the Astar pilot’s attention was on his sling load. He did not see the Bell 206L take off. Once he saw the Bell 206L appear in his floor sling window, he attempted a rapid climb. However, this evasive action was not successful in preventing the collision.

Although a potential risk had been identified with the high volume of traffic using the fuel-staging area, the radio reporting procedures were considered satisfactory by the various flight crews operating in the area. Prior to the occurrence, plans to move several fuel tanks to a different location had been discussed. The fuel-staging area was not congested at the time of the occurrence and traffic volume in the area was not considered to have contributed to the event.

Findings as to causes and contributing factors

  1. No broadcast was heard stating the Bell 206L pilot’s intention to take off and the Astar pilot was not aware that the Bell 206L was about to take off.
  2. Although not mandatory to do so, the Bell 206L pilot did not execute a left hover turn prior to taking off to ensure there was no traffic or obstacles in his intended departure path. Without this safety check prior to takeoff, the Bell 206L pilot could not see the Astar and its sling load coming from behind and from the left.
  3. Although not mandatory, the Astar pilot did not broadcast his position on final approach or on short final.
  4. It is likely that the Bell 206L pilot had not yet donned his headset or had not yet powered the radios and, therefore, did not hear either of the Astar pilot’s previous position reports.

Finding as to risk

  1. Uncontrolled airports pose an additional risk for users and although it is good airmanship to communicate on the published ATF, it is not mandatory by regulation to do so.

Safety action taken
Prior to this occurrence, the helicopter operators, the exploration companies, and the Postville town council had agreed to relocate several of the fuel tanks in order to alleviate the amount of traffic using the fuel-staging area. These plans were awaiting the appropriate permits. Since the occurrence, a new fuel-staging area has been prepared.

The operator briefed all of its crews working in the Postville area to increase the frequency of their position reports, to call on short final and to also call before departure.

TSB Final Report A08W0068—Loss of Control—In-Flight Breakup

On March 28, 2008, a privately operated Piper PA-46-350P Jetprop DLX had departed Edmonton, Alta., at about 07:33 Mountain Daylight Time (MDT) en route to Winnipeg, Man., on an IFR flight plan. Shortly after the aircraft levelled off at its cleared altitude of FL270, the aircraft was observed on radar climbing through FL274. When contacted by the controller, the pilot reported having autopilot and gyro-horizon problems and difficulty maintaining altitude. Subsequently, he transmitted that his gyro-horizon had toppled and could no longer be relied upon for controlling the aircraft.

The aircraft was observed on radar to make several heading and altitude changes before commencing a right turn and a steep descent, after which the radar target was lost. An emergency locator transmitter (ELT) signal was received by the Lloydminster, Alta., flight service station (FSS) for about 1½ min before it stopped. The wreckage was found by the Royal Canadian Mounted Police (RCMP) about 16 NM northeast of Wainwright, Alta., at about 12:05 MDT. None of the five people on board survived.

Photograph of accident area

Findings as to causes and contributing factors

  1. The gyro-horizon failed due to excessive wear on bearings and other components, resulting from a lack of maintenance and due to a vacuum system that was possibly not at minimum operating requirements for the instrument.
  2. The gyro-horizon was reinstalled into the aircraft to complete the occurrence flight without the benefit of the recommended overhaul.
  3. The autopilot became unusable when the attitude information from the gyro-horizon was disrupted.
  4. The pilot had not practised partial panel instrument flying for a number of years, was not able to transition to a partial panel situation, and lost control of the aircraft while flying in instrument meteorological conditions (IMC).
  5. The aircraft was loaded in excess of its certified gross weight and had a centre of gravity (C of G) that exceeded its aft limit. These two factors made the aircraft more difficult to handle due to an increase of the aircraft’s pitch control sensitivity and a reduction of longitudinal stability.
  6. The structural limitations of the aircraft were exceeded during the uncontrolled descent; this resulted in the in-flight breakup.
  7. There were a number of deficiencies with the company’s safety management system (SMS), in which the hazards should have been identified and the associated risks mitigated.
  8. The company did not conduct an annual risk assessment as required by its SMS; this increased the risk that a hazard could go undetected.
  9. The Canadian Business Aviation Association (CBAA) audit did not identify the risks in the company’s operations. 

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