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Recently Release TSB Reports

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 http://www.tsb.gc.ca/. —Ed.

• TSB Final Report A06P0095—Loss of Control
• TSB Final Report A06O0141—Loss of Control and Collision with Terrain
• TSB Final Report A06O0180—Collision with Water
• TSB Final Report A06C0131—Collision with Terrain
• TSB Final Report A06Q0180—Loss of Electrical Power
• TSB Final Report A07Q0014—Fuel Starvation
• TSB Final Report A07Q0085—In-Flight Break-Up
• TSB Final Report A08W0096—Loss of Control and Collision with Terrain

TSB Final Report A06P0095—Loss of Control

On May 31, 2006, the pilot of a Cessna 185B departed Prince George, B.C., from Runway 19 on a flight to Scoop Lake, B.C. The aircraft flew on the runway heading until it was about 2400 ft beyond the departure end of the runway, where it abruptly pitched up, climbed steeply, turned left, and rapidly descended into trees about 600 ft left of the runway’s extended centreline. The aircraft was airborne for less than 47 s and reached a maximum height of about 270 ft above ground level (AGL). The aircraft was destroyed, and the pilot, who was the sole occupant, was seriously injured. There was no fire.

Analysis
There are many indications that the engine was operating normally, making engine failure unlikely as a cause or contributing factor to the accident.

The take-off distance and climb speeds were consistent with the performance indicated in the owner’s manual.

The aircraft’s centre of gravity (CG) was near the aft limit and the flight path after takeoff was consistent with an aircraft that is aft-heavy and unstable about the pitch axis. The horizontal stabilizer was found trimmed to a position consistent with an aft CG. The turbulent, gusty wind at Prince George and the retraction of the flaps would have exacerbated the unstable condition. As well, the unrestrained cargo may have shifted rearward in flight, moving the CG further aft.

It is concluded that a loss of pitch control, consistent with an aft CG, occurred in gusty and turbulent conditions at a height too low for the pilot to effect recovery. The unrestrained cargo likely struck the pilot during the crash and may have contributed to his injuries.

Findings as to causes and contributing factors

1. Loss of pitch control, consistent with an aft CG, occurred in gusty and turbulent conditions at a height too low for the pilot to effect recovery.
   
2. The cargo was unrestrained, which may have allowed some cargo to shift rearwards during the takeoff and climb, resulting in an extremely aft CG.

Finding as to risk

1. Unrestrained cargo presents a high risk to aircraft occupants during turbulence and during a crash.

TSB Final Report A06O0141—Loss of Control and Collision with Terrain

On June 16, 2006, the pilot of the privately owned Bede BD5-JM aircraft departed the Ottawa/Carp Airport, Ont., at approximately 12:05 Eastern Daylight Time (EDT) to practice his routine for the air show scheduled for the following two days. At approximately 12:10 EDT, the pilot radioed that he was starting his final fly-past before landing. The routine for this low-speed fly-past called for a number of quick extensions and retractions of the aircraft’s landing gear while at a height of about 500 ft above ground level (AGL). After several cycles of the landing gear, and while the landing gear was extended, the aircraft rolled sharply to the right. The nose dropped, and the aircraft descended rapidly and hit the ground. The aircraft was substantially damaged, and the pilot sustained fatal injuries.

Finding as to causes and contributing factors

1. The right flap was incorrectly installed during the wing installation, which allowed the right flap to retract during the fly-past. This created a flap asymmetry that resulted in an uncommanded and uncontrollable right roll. The aircraft was at an altitude from which recovery was not possible before the aircraft struck the ground.

Findings as to risk

1. The right-wing taper bolt did not penetrate deep enough through the spars to engage the fibre locking feature of the locknut. Therefore, the taper bolt was not in safety at the time of the accident.
   
2. The fibre locking feature of the left-wing locknut was worn and did not secure the left-wing taper bolt in safety.

TSB Final Report A06O0180—Collision with Water

On July 16, 2006, at approximately 17:20 Eastern Daylight Time (EDT), a float-equipped Cessna 172M aircraft was departing Wilcox Lake, Ont., for a flight to Manitoulin Island, Ont., in visual meteorological conditions (VMC). Because of the confined area of the lake, the pilot performed a figure-eight manoeuvre while step-taxiing to increase speed for the final take-off run. This manoeuvre entailed two 180° turns at opposite ends of the lake. After the aircraft became airborne, a steep, low-altitude turn to the left was initiated to avoid obstacles on the shoreline. As the bank angle increased, the aircraft stalled, struck the water in a nose-down attitude with the left float, and flipped over. The aircraft came to rest inverted in shallow water near the shoreline. The pilot and two passengers escaped without injury.

Wilcox Lake is a small lake in a residential area of Richmond Hill, Ont. The shoreline is surrounded by residential buildings, and beyond that, numerous subdivisions. The lake is popular for recreational activities such as swimming, boating, and canoeing; during the occurrence, it was being used extensively. The longest section of the lake is approximately 3500 ft in an east-west direction. The direction the aircraft was travelling during the final take-off run was northwest. The total distance available from the southeast shoreline to the northwest shoreline for the take-off run was about 2500 ft.

The figure-eight manoeuvre that was used during the takeoff entailed changing direction twice and, because of the speed of the aircraft, a large radius turn could be expected. The aircraft was approximately 200 ft from the east-southeast shoreline before turning to a northwest direction for the final take-off run. There is an inherent risk related with changing directions while step taxiing, depending on the associated wind and wave conditions. During a step taxi turn from a tailwind to a headwind, the wind acts on the underside of the inboard wing, causing it to rise. This, combined with upward movement caused by wave action and pressure from centrifugal forces acting on the aircraft during the turn, can lead to the aircraft capsizing.

The occurrence take-off procedure was self-taught and was not published in the Cessna pilot operating handbook as a normal or amplified procedure. According to the Canadian Aviation Regulations (CARs), the manoeuvre was not a required procedure to learn or demonstrate for a seaplane rating.

The distance available for takeoff into wind, in a northwest direction, was insufficient. While there was enough distance to get airborne, the aircraft would not have been able to climb safely to an obstacle clearance altitude of 50 ft. The pilot elected to use a step-taxi turn in an attempt to shorten the take-off run. However, this had a negligible effect because the turn radius of the aircraft was increased during the final turn, thereby shortening the into-wind take-off distance available. After liftoff, the slow speed of the aircraft did not provide much margin above the stall speed for manoeuvring. As the aircraft banked to avoid obstacles, the stall speed increased, and the aircraft stalled.

The wind and wave conditions at the lake during the occurrence presented a risk of capsizing the aircraft during the step-taxi, figure-eight manoeuvre. The manoeuvre also introduced a potential conflict with watercraft and other persons using the lake for recreational purposes. A takeoff conducted in a fixed direction would have reduced the risk of collision.

Findings as to causes and contributing factors

1. The pilot attempted to take off into wind in a northwesterly direction, although the distance available to take off and clear a 50-ft obstacle was insufficient.
   
2. After becoming airborne with insufficient distance remaining to clear the obstacles ahead, the pilot attempted a steep turn at low altitude, resulting in a stall and impact with the water.

Findings as to risk

1. During the step-taxi, figure-eight manoeuvre, because of the associated wind and wave conditions, the aircraft was at risk of capsizing.
   
2. The aircraft was step-taxied in a manner that introduced a potential risk of collision with watercraft and other people using the lake.
   
3. The figure-eight, take-off manoeuvre employed by the pilot further decreased the into-wind take-off distance available because of the large radius turn of the aircraft while on step.
   
4. There is no indication that any of the pilot recency requirements under CAR 401.05(2)(a) were complied with.

Other finding

1. Due to the absence of a maintenance release for the vortex generator installation, the aircraft was not being operated in accordance with CAR 605.85.

TSB Final Report A06C0131—Collision with Terrain

On August 13, 2006, the pilot of a McDonnell Douglas Hughes 369E helicopter was transporting a team of two line-cutters from their company’s base camp in the vicinity of Davy Lake, Sask., to nearby line-cutting operations. The pilot was flying at altitudes from 300 to 500 ft above ground level (AGL) in the vicinity of a small, unnamed lake when a caribou was spotted swimming across the lake. The pilot turned and descended toward the animal. The helicopter subsequently struck the lake at about 100 kt, at approximately 08:30 Central Standard Time (CST). The helicopter sank soon after impact, but the three occupants were able to egress from the submerged wreckage. The pilot and one passenger, who had both sustained serious injuries, were able to swim to shore. After removing their work clothing, they swam back to rescue the second passenger who was in difficulty in the water. Their attempt was unsuccessful and the second passenger drowned. The two survivors were rescued later that afternoon.

Other factual information
The pilot was flying the helicopter from the left seat. One passenger was in the front right seat and the other passenger was seated in the right rear seat. When the caribou was spotted in the water, the pilot began a right turn toward the lake, leaning forward during the turn to keep the caribou in view. A steep descent developed over the trees and the pilot initiated recovery. The flight path of the helicopter continued over the water, paralleling a portion of the shoreline approximately 100 ft from the shore. The pilot continued levelling the helicopter but did not perceive that collision with the water was imminent and flew the helicopter into the water. For the operating conditions at the time of the accident, the helicopter’s never exceed speed(V_ne) was 130 kt. There was no report of any unusual control forces, warning lights, or warning horns before or during the descending turn.

Fascination is a condition in which the pilot fails to respond adequately to a clearly defined stimulus situation, despite the fact that all of the necessary cues are present and the proper response is available to him. This is commonly referred to as “target fixation” and is fundamentally perceptual in nature. The individual concentrates on one aspect of the total situation to such a degree that he rejects other factors in his perceptual field.

A second perceptual problem occurs over water in conditions of very light or no wind. The water surface is featureless without wave action, commonly called “glassy water,” and makes accurate judgement of height above the water impossible. The pilot can experience the illusion that he is higher than he actually is. The pilot in this occurrence had no knowledge of the glassy water phenomenon.

Analysis
Although the pilot had completed pilot decision-making training, he did not apply these principles when deciding to manoeuvre and observe the caribou. The decision was made without consideration of the safety issues for over-water flight or knowledge of the hazards of the glassy, or near glassy, water phenomenon. The pilot likely fixated on the caribou and lost situational awareness, thereby allowing the helicopter to enter a high rate of descent at low altitude. When the pilot became aware that the helicopter was in a steep descent over the trees, he attempted to stop the descent but the helicopter continued out over the water surface. It is likely that difficulty with height judgement over glassy or near-glassy water impeded his recovery. Consequently, he flew the helicopter into the lake at high speed while attempting to level off.

Finding as to causes and contributing factors

1. The pilot lost situational awareness while turning and entered a high rate of descent at low level. The recovery stage continued over glassy or near-glassy water and the pilot flew the helicopter into the water at high speed.

Finding as to risk

1. Serviceability inspections of the helicopter did not detect the fatigue crack developing in the support arm.

Safety action taken
On February 20, 2007, the TSB issued Safety Information Letter A06C0131-D1-L1, Pre-Crack/Fatigue Crack of the Tail Rotor Gearbox Bellcrank Support Horn, to Transport Canada Civil Aviation (TCCA). The Safety Information Letter stated that, in this occurrence, an inspection of the wreckage revealed a suspicious fracture surface of the tail rotor gearbox bell crank support horn.

Analysis of the fracture revealed a pre-crack/fatigue crack extending across approximately 75 percent of the entire cross section of the bell crank support horn. The fractured horn did not contribute to the accident.

On March 30, 2007, TCCA responded to the letter, indicating that it had been provided to the appropriate departmental officials for their information and use.

TSB Final Report A06Q0180—Loss of Electrical Power

On October 18, 2006, a Beechcraft King Air 100, with two pilots and four passengers on board, took off at 09:18 Eastern Daylight Time (EDT) from the Montréal/Pierre Elliott Trudeau International Airport, Que., on an IFR flight inbound to Montréal/St-Hubert Airport, Que. Shortly after takeoff, the generation of electrical power ceased, followed by a complete loss of radio navigation equipment, some flight instruments, most engine instrument panel indicators, and a radio communication failure. The crew left the assigned altitude to descend to the minimum sector altitude. A break through the clouds allowed the aircraft to descend below the cloud cover. The crew continued the flight under VFR, and the aircraft landed without further incident at the Montréal/St-Hubert Airport. There were no injuries or damage to the aircraft.

Findings as to causes and contributing factors

1. Shortly before takeoff, the pilot-in-command inadvertently selected the ignition and engine start switches instead of the auto-ignition switches. As a result, all of the aircraft’s electrical needs were powered by the battery, which was unable to maintain the load needed for the normal use of the electrical system and its related instruments.
   
2. The line-up checklist does not require a load indicator reading when the auto-ignition switches are selected, which would confirm that the generators are on-line.
   
3. The absence of a clear indication by the warning lights that the generators were off-line precluded the crew from the information needed to quickly recognize the anomaly.
   
4. The crew completed the “abnormal gear indication-in transit” checklist. This checklist gives the impression that no other procedures are available to rectify the situation and does not refer the flight crew to the “landing gear will not retract” checklist.
   
5. The crew did not complete the “landing gear will not retract” checklist; if it would have done so, the electrical power could have been cut to the landing gear motor. The energy saved would have kept the radios and flight instruments operational for several minutes.

Finding as to risk

1. The crew descended to an altitude below the sector altitude applicable to its position, without knowing its exact position. This situation increased the risk of collision with the terrain or with obstacles.

Other findings

1. The absence of a formal process for analyzing operational experiences and the lack of disclosure of information on previous similar accidents or incidents allowed the same situation to recur under more difficult conditions.
   
2. The crew encountered overlapping failures, and did not have the time to complete the checklists specific to each failure, which, eventually, would have helped rectify the situation. Instead, the crew decided to descend to regain and maintain visual contact with the ground.

Safety action taken
Since this incident, during initial and recurrent ground training, the operator’s instructors emphasize the risk associated with the starter/generator system and its consequences on some of the company’s Beechcraft King Air 100.

TSB Final Report A07Q0014—Fuel Starvation

On January 21, 2007, a ski-equipped DHC-2MKI Beaver took off around 11:30 Eastern Standard Time (EST) from Mirage Outfitter, located 60 mi. east of LaGrande-4 Airport, Que., with a pilot and four passengers on board, to locate caribou herds. About 40 min after departure, the engine stopped as a result of fuel starvation. The pilot was not able to regain power and made a forced landing on rugged ground. The aircraft was heavily damaged and two passengers were seriously injured. The pilot used a satellite telephone to request assistance. First-aid assistance arrived by helicopter about 1hr30 min after the occurrence. The aircraft fuel system had been modified after the installation of wings made by Advanced Wing Technologies Corporation.

Findings as to causes and contributing factors

1. The engine stopped as a result of fuel starvation; the amount of fuel in the wings was less than the amount estimated by the pilot, the fuel senders gave an incorrect reading, and the low fuel pressure warning light could illuminate randomly.
   
2. The engine stopped at low altitude, which reduced the time needed to complete the emergency procedure. The pilot was unable to glide to the lake and made a forced landing on unsuitable terrain, causing significant damage to the aircraft and injuries to the occupants.

Findings as to risk

1. The wing tank selection system was subject to icing in cold weather, and the pilots adopted the practice to place the wing tank selector in the middle position, which is contrary to the aircraft flight manual supplement instructions and a placard posted on the instrument panel.
   
2. When the change to the type design was approved through issuance of the Supplementary Type Certificate (STC), Transport Canada did not notice the fact that the fuel senders and triple fuel level gauge did not meet airworthiness standards; Transport Canada issued an STC that contained several deficiencies.
   
3. Storage of the shoulder harnesses underneath the aircraft interior covering made them inaccessible; since the pilot and the front seat passenger did not wear their shoulder harness, their protection was reduced.

TSB Final Report A07Q0085—In-Flight Break-Up

On May 27, 2007, a Eurocopter AS350 B1 Astar helicopter departed a mining camp 176 NM northeast of Chibougamau, Que., at 08:00 Eastern Daylight Time (EDT) en route to a drill site 20 NM to the southeast. Approximately four minutes after departure, the helicopter broke up in flight and descended rapidly to the ground. The pilot, the sole occupant, was fatally injured and the aircraft was destroyed.

Analysis
The TSB post-accident examination revealed that the snap ring within the main gearbox (MGB) epicyclic reduction gear module was installed before installing the spacer assembly. The wrong installation sequence of the snap ring, relative to the spacer assembly, allowed the snap ring to slip from its groove on the mast, which in turn prevented the locking tabs from holding the mast retaining bolts. The bolts loosened by rubbing inside the sun gear, and eventually fell out, allowing the main rotor shaft to move vertically. The vertical movement of the main rotor shaft caused the rotor blades to strike the forward fuselage.

Findings as to causes and contributing factors

1. The aircraft maintenance engineers (AME) did not consult the applicable sections of the work card (WC) for the re-installation of the main rotor shaft and the MGB epicyclic reduction gear module. This resulted in the snap ring being installed in the wrong sequence.
   
2. The wrong installation sequence of the snap ring ultimately allowed the mast retaining bolts to loosen and the mast to move vertically, causing the rotor blades to strike the forward fuselage.

Findings as to risk

1. The symptoms experienced during ground-runs and test flights, and noted during flights following the maintenance, demonstrated a previously undiscovered link to the incorrect assembly of the MGB epicyclic reduction gear module. Current maintenance manual (MM) troubleshooting instructions do not direct AMEs to a possible MGB epicyclic reduction gear module assembly problem.
   
2. Referring AMEs to lengthy instructions, not necessarily required in full, may result in a filtering process that causes important information to be missed.
   
3. The maintenance manual specifies that the same number of threads should be visible on the main rotor shaft retaining bolts during the borescope inspection, but it does not specify the actual number of threads that should be visible to confirm proper installation. Therefore, the installation could appear to be secure when it is not.

Safety action taken
Subsequent to this occurrence, Eurocopter took the following actions:

• Issued a Telex Information Letter (T.F.S.No.00000393 dated 15 June 2007) titled Main Rotor Mast Equipped with a 4-contact Bearing. Assembly of the spacer/phonic wheel with respect to the retaining ring. This telex acts as an initial information letter to all operators prior to a final document amendment. The telex clarified compliant installation of t
• he snap ring.
• Changed its documentation and added a new assembly diagram to WC 62.30.16.701 to ensure a better applicability of the assembly procedures.
• Modified WC 05-53-00-614 for related troubleshooting details.
• Deleted the borescope inspection within the MM 63.10.16.403 and the WC 62.30.16.701.
• Changed the material of the snap ring from steel to elastomeric, making the assembly tolerant to potential assembly error. The new elastomeric ring will shear if it is not installed in the proper order under the torquing loads of the mast retaining bolts. This will result in the assembly becoming secure by all the required contact points.

TSB Final Report A08W0096—Loss of Control and Collision with Terrain

On May 24, 2008, a MacDonnell Douglas Helicopters Inc. (MDHI) 369D helicopter was transporting drilling personnel near Doctor Lake, N.W.T. Near the landing site, the pilot had been hovering into wind at approximately 300 ft above ground level (AGL) to determine the best footpath between a water body and a landing pad; once this had been accomplished, the aircraft was in the process of descending and hovering sideways to the left with the nose into wind toward the landing pad. At about 75 ft AGL, the aircraft started an uncommanded rotation to the right and crashed. The helicopter was substantially damaged by impact forces and a post-crash fire. The pilot was seriously injured, one of the two passengers was fatally injured, and the other suffered minor injuries.

Analysis
The maintenance and airworthiness of the helicopter, as well as weather, were not considered contributory factors in this accident. Main rotor and engine crash signature indications confirm that the engine was operating at the time of impact. Therefore, the engine is also not considered a contributory factor in this occurrence.

At the time of the uncommanded right rotation, the helicopter was hovering laterally to the left. The relative wind was outside the critical azimuth, and the rotation resumed after the pilot re-applied engine power. It is therefore unlikely that an airflow effect induced the rotation.

Damage to the aircraft indicated virtually no rotation of the tail rotor at the time of ground contact, but there was evidence of low-power main rotor rotation. The engine was producing power but this power was not being transferred to the tail rotor. It was most likely that the tail rotor drive shaft failed at the forward section, but evidence to confirm this was lost in the post-crash fire. Failure of the tail rotor drive shaft would result in an uncommanded rotation of the helicopter around the vertical axis. The helicopter response to changes in throttle setting corresponds to what would be expected for a loss of tail rotor drive. There was insufficient altitude to effect recovery before ground impact.

Finding as to causes and contributing factors

1. It is likely that the tail rotor drive shaft failed, which resulted in an uncommanded rotation of the helicopter at an altitude from which recovery was not possible.

Safety action taken
The operator initiated a special inspection and measuring process on the forward section of selected tail rotor drive shafts operating in its fleet for this model of helicopter, in addition to the requirements of the maintenance manual inspection criteria.

Date modified:

2010-05-20

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