Recently Released TSB Reports Recently Released 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. For more information, contact the TSB or visit their Web site at www.tsb.gc.ca. —Ed.

TSB Final Report A07P0209—Tail Rotor Driveshaft Fracture

On July 2, 2007, a Bell 214B1 helicopter was carrying out heli-logging operations in Ramsay Arm, B.C. At about 08:00 PDT, the helicopter was in a 200-foot hover and starting to pick up the 11th load when the two pilots noted a loud growling sound from within the helicopter. Immediately, the flying pilot discontinued the lift and released the load from the longline hook. He then flew the helicopter back towards the nearby service area to have the noise investigated. About 20 sec later, just as the helicopter entered a high hover above the service landing site, the growling noise stopped, the low oil pressure warning lights for the two tail rotor gearboxes illuminated, and the helicopter rotated quickly to the right. The pilot was unable to stop the rotation using the tail rotor control pedals and the helicopter made two or three 360° turns to the right. The pilot rolled off the throttle on the collective stick and attempted to land in trees adjacent to the service area. The helicopter descended upright and struck several trees before landing hard on the uneven terrain. The flying pilot, seated in the left hand seat, was seriously injured and the co-pilot received minor injuries. The helicopter was substantially damaged during the landing and there was no fire. The emergency locator transmitter activated at impact and survived the crash.

Bell 214B1 wreckage
Bell 214B1 wreckage

Findings as to causes and contributing factors

  1. The tail boom had been subjected to extreme heat from the engine exhaust during its service life and, over time, certain tail boom skin panels developed structural weaknesses.
  2. The reduction in the strength and stiffness of the tail boom skin in the area damaged by exhaust gas heating likely allowed the tail boom to distort excessively under high-power settings.
  3. The No. 3 tail rotor driveshaft segment broke as a result of severe scoring caused by heavy contact with the tail boom, which was precipitated by tail boom distortion.
  4. The No. 3 tail rotor driveshaft was also subject to in-flight bending that likely exacerbated the heavy contact with the distorted tail boom.
  5. Had the pilot-in-command been wearing the available upper body restraint (shoulder harness), his injuries would have been lessened.

Findings as to risk

  1. The lack of documented service history for the tail rotor driveshaft prevented effective traceability of a condition-monitored component that was essential to the continued operation of the helicopter.
  2. Vertical reference flying necessitates upper body freedom of movement, typically resulting in the non-use of the shoulder harness. This exposes pilots to greater injury in the event of a collision with the terrain.
  3. Most helicopters are not designed to accommodate vertical reference flying techniques, and certification for external load operations does not take them into account, thus increasing the risk of injury in a collision.
  4. The withholding of engineering information and tests by manufacturers impairs the timely discovery of accident causes, denying operators vital information and the opportunity to avoid their re-occurrence.

Other finding

  1. The pilot's flight helmet prevented life-threatening head injuries during the collision with terrain; many Canadian helicopter operators encourage their pilots to wear helmets in most operational environments.

Safety action taken

As a result of the investigation into this Bell 214B1 accident, the operator has voluntarily chosen to replace its Bell 214B1 tail boom skins every 5 000 flight hr. Another operator, which is also a maintenance, repair and overhaul facility for this model, said it will replace its tail boom skins every 3 000 hr.

TSB Final Report A07W0128—Collision at Takeoff

On July 8, 2007, at approximately 12:35 PDT, a de Havilland DHC-6-100 Twin Otter was taking off from a gravel airstrip near the Northern Rockies Lodge at Muncho Lake on a visual flight rules flight to Prince George, B.C. After becoming airborne, the aircraft entered a right turn and the right outboard flap hanger contacted the Alaska Highway. The aircraft subsequently struck a telephone pole and a telephone cable, impacted the edge of the highway a second time, and crashed onto a rocky embankment adjacent to a dry creek channel. The aircraft came to rest upright approximately 600 ft from the departure end of the airstrip. An intense post-impact fire ensued and the aircraft was destroyed. One passenger suffered fatal burn injuries, one pilot was seriously burned, the other pilot sustained serious impact injuries, and the other two passengers received minor injuries.

DHC-6-100 Twin Otter crash

Analysis

The weather conditions were suitable for visual flight and field examination of the wreckage gave no indication that a pre-occurrence mechanical problem had contributed to the accident. Although the performance of the left engine was slightly less than that of the right engine during the take-off roll, the torque pressure on both engines exceeded the expected take-off power setting of 39.5 psi torque pressure for the existing temperature and pressure altitude, and the propeller rpms compared favourably with normal take-off values. The analysis will therefore discuss the organizational and management factors that contributed to the aircraft being operated outside of its performance capabilities on the accident takeoff.

Organizational and management factors

The operational control and the risk management practices that existed within the operator did not recognize and reduce or eliminate the risks associated with takeoffs from the lodge airstrip. The operator was in a state of administrative transition at the time of the accident due to several recent changes in key personnel; the Twin Otter operation was most affected by this transition.

A number of organizational policies and procedures that may have prevented the accident were either violated, not used, or missing. The operator's operations manual was written to ensure safe flight operations and to eliminate potential errors in flight crew judgement. Although a weight and balance calculation had been accomplished prior to the accident flight, the aircraft weight was not used to calculate take-off performance, as required by the operations manual. Takeoffs from the lodge airstrip had come to be regarded as routine, without a need to calculate take-off performance prior to each departure, and aircraft loading was based mostly on the intuition and judgement of the owner and/or flight crews.

The operator had an unwritten company policy that the lodge airstrip would be used primarily to store the Twin Otter and that Twin Otter departures from the airstrip would be carried out with crew only and minimum fuel on board. Records of previous takeoffs from the airstrip indicated that the policy of not carrying passengers out of the lodge airstrip was rarely violated, although takeoffs were occasionally accomplished with heavy fuel loads. On the day of the accident, this policy was violated in two ways: the takeoff was attempted with three passengers and the aircraft had a full load of fuel.

Training provided by the owner to the captain emphasized the use of 30° of flap for short-field takeoffs when 10° of flap would have resulted in lesser distance to climb to 50 ft. Considering the elevation, length, slope, and gravel surface at the lodge airstrip, maximum performance short takeoff and landing (MPS) procedures may have been required at times for higher weight takeoffs; however, neither the company nor the aircraft were approved for MPS operations and neither flight crew member had received appropriate MPS training.

The operator's owner was the main decision-maker within the company. He was entirely familiar with the company's daily operations, he was highly influential with respect to how flights were to be carried out, and he had significant experience with Twin Otter operations on the lodge airstrip. These elements, combined with his direct input at the pre-flight planning phase of the accident flight, contributed to the flight crew expectation that the takeoff could be accomplished successfully. As well, the regular direct oversight that he provided in the Twin Otter operation may have resulted in ambiguity with regard to the duties and responsibilities of those involved with the Twin Otter operation.

Despite regular use of the lodge airstrip and recognition by the owner that take-off weights were a critical consideration in these operations, there was no standard operating procedure (SOP) for Twin Otter short-field operations. An applicable SOP would have formalized and set the non-MPS limits for short field operations, thereby reducing the risk associated with lodge airstrip operations.

Lodge airstrip in direction of takeoff
Lodge airstrip in direction of takeoff

Work setting

The work setting and work expectations at the operator were unlike those found in the corporate or airline environments that were most recently familiar to the captain and the first officer. The operational support provided in corporate and airline operations, in the form of dispatchers, ground crews, locally available maintenance personnel, and highly-formalized operational procedures rarely exist in similar small, seasonal bush-flying operations. As a result, flight crews working for seasonal bush-flying operators often rely heavily on local knowledge gained through experience with a particular operator and are typically more self-reliant when it comes to making day-to-day operational decisions. As well, the operational challenges encountered in confined, short-airstrip environments can be significantly different from those encountered in corporate and airline operations, where longer runways and obstacle-free climb-out corridors are the norm.

Flight crew

The captain and the first officer were themselves the final line of defence in the system. Both were relatively new to the operator's working environment and to lodge airstrip operations. The captain had been hired and appointed chief pilot about five weeks prior to the accident. His initial administrative workload as chief pilot and his flight duty obligations were significant, which may have reduced the time available to experience, recognize, and evaluate the risks associated with the operator's flight operations from the lodge airstrip. Critical information regarding the accident flight was provided to the captain in a somewhat piecemeal fashion between the time of the original early morning discussion and the departure; however, the captain expected the takeoff would be successful, based on his belief that both the owner and the first officer had discussed and considered the take-off weight.

The first officer was more familiar than the captain with the circumstances leading up to the flight, having taken most of the morning to prepare the aircraft. His expectation of a successful takeoff was likely based on his conversations with the owner and the captain. He verbally provided the captain with weight and balance information; aside from that, he appears to have placed full responsibility for the decision to attempt the takeoff on the captain, who was only peripherally involved with the flight planning.

The captain had recently been flying DHC-6-300 series aircraft in the Maldives. Although that experience involved only float-equipped Twin Otters, his recent familiarity with the higher performance capabilities of the DHC-6-300 series aircraft may have conditioned him to anticipate a higher level of aircraft performance in the operator's DHC-6-100 series operations. As well, both pilots were aware that the aircraft had been operating out of the lodge airstrip for several years, which reinforced their expectation that the takeoff should be successful.

Pre-flight planning

Pre-flight planning is an essential component of any flight and flight crews are required by regulation to avail themselves of all obtainable information pertinent to a flight prior to departure. Because the DHC-6 Twin Otter is a very capable short-field aircraft, it is commonly used on short, unprepared airstrips where there is little margin for error in flight crew judgement or performance. In all cases when operating in short-field environments, it is imperative that flight crews recognize and operate within the take-off performance limitations of the aircraft.

Pre-flight load planning for the accident flight primarily involved the owner and the first officer. The captain agreed to take off from the lodge airstrip with one passenger. He went flying soon after and had no direct input into the later decisions to add full fuel and two extra passengers to the flight. The owner also went flying and was therefore no longer in a position to closely monitor the progress of the pre-flight preparations or consider the addition of a third passenger on the aircraft. Although the first officer spent most of the morning preparing the aircraft, he prepared only a weight and balance report and did not complete a take-off performance calculation.

Critical information regarding the significance of surface wind, temperature, and aircraft weight on operations specific to the lodge airstrip may not have been communicated to the flight crew during training. Despite changes in wind and temperature conditions and the much higher than normal take-off weight for lodge airstrip departures, neither pilot recognized the need to reconsider the takeoff weight. The final decision to attempt the takeoff represented a collective failure on the part of the owner, the captain, and the first officer to recognize and manage the risks associated with lodge airstrip operations.

Takeoff

The aircraft was not positioned so as to use the entire airstrip before commencing the takeoff and the brakes were released prior to the engines achieving take-off power. Both of these elements made it less likely that the aircraft would achieve the necessary obstacle clearance altitude. The use of the lodge airstrip left no margin for error and once the take-off roll began, there was little time to evaluate the aircraft's performance and if necessary reject the takeoff. Had the flight crew identified a suitable reject point for the takeoff and had the takeoff been rejected due to the aircraft not being airborne at that point, the accident risk would have been reduced.

The aircraft used most of the available airstrip during the takeoff and drifted approximately 20° to the left during the latter part of the takeoff for unknown reasons. This required the initiation of a steep bank to remain over the highway corridor on climb-out that reduced the climb performance of the aircraft and increased the likelihood of the aircraft contacting the telephone cable.

Considering the airstrip length and slope, the wind and the temperature conditions, the location of the telephone cable, and the take-off procedures that were used, the takeoff was attempted at a weight that exceeded the obstacle clearance performance capabilities of the aircraft. Had a take-off performance calculation been accomplished prior to take off, it would have identified that the distance available was inadequate for takeoff under these conditions.

Findings as to causes and contributing factors

  1. The takeoff was attempted at an aircraft weight that did not meet the performance capabilities of the aircraft to clear an obstacle and, as a result, the aircraft struck a telephone pole and a telephone cable during the initial climb.
  2. A takeoff and climb to 50 ft performance calculation was not completed prior to takeoff; therefore, the flight crew was unaware of the distance required to clear the telephone cable.
  3. The southeast end of the airstrip was not clearly marked; as a result, the takeoff was initiated with approximately 86 ft of usable airstrip behind the aircraft.
  4. The takeoff was attempted in an upslope direction and in light tailwind, both of which increased the distance necessary to clear the existing obstacles.

Safety action taken

Following the accident, Transport Canada conducted a regulatory audit on the company. The Twin Otter was not replaced and the operator voluntarily gave up the Canadian Aviation Regulation section 704 privileges on the company's air operator certificate.

Following this accident, the owner initiated the following corrective action within the operation:

  1. Every pilot employed by the operator will receive and be required to read and sign a letter that summarizes the pilot's responsibilities in the operation of the operator's aeroplanes.
  2. The operator purchased and installed satellite telephones in each floatplane to improve direct communication between pilots.
  3. The operator's Maintenance Control Manual has been amended to require any seatbelt in any company aircraft to be replaced after 10 years, even if the manufacturer has not put a life on the seatbelt.
  4. Weight and balance samples for various loading configurations in company aircraft have been calculated and a computer program is now in use for weight and balance calculations at the home base. The weight and balance calculations and the formulas used will only be the ones issued by the aeroplane manufacturer.

TSB Final Report A07O0314—In-flight Engine Failure

On November 23, 2007, an Aerospatiale AS 350 B3 helicopter was en route from London, Ont. to Windsor, Ont. at 2 000 ft ASL. At approximately 07:55 EST, the helicopter yawed sharply to the right, the rotor rpm dropped, the engine chip and governor light illuminated, and the warning horn sounded. The engine (a Turbomeca Arriel 2B) had failed and the pilot commenced an autorotation landing into a farm field. During the descent, the pilot transmitted a mayday call and activated the emergency locator transmitter. The helicopter landed without further incident. There were no injuries and the helicopter was not damaged. The pilot completed the shutdown checklist and switched off the battery.

Aerospatiale AS 350 B3 helicopter
AS 350 sitting in the field after the successful autorotation
with no damage at all. Great job by the pilot!

An examination of the engine determined that the 41-tooth bevel gear (part number 0292127330) had fractured due to high-cycle fatigue cracking. The gear was installed during engine manufacture and had accumulated a total of 1 644 hr since new. Metallurgical examination (TSB Laboratory report LP 005/2008) of the bevel gear revealed numerous fatigue cracks radiating from the roots of many of the gear teeth. Circumferential fatigue cracks were also observed in the rim of the gear. There were no relevant manufacturing flaws found in the gear that could contribute to the failure.

Fractured 41-tooth bevel gear shown with other parts from the accessory gearbox
Fractured 41-tooth bevel gear shown with
other parts from the accessory gearbox

Findings as to causes and contributing factors

  1. The 41-tooth bevel gear of the accessory gearbox module 1 (MO1) accessory gear box failed due to high-cycle fatigue causing an uncommanded in-flight engine shutdown.
  2. The dampening system of the starter-generator was found to be over-tightened which caused torsional oscillations (vibration) under certain operational conditions. This most likely contributed to the high-cycle fatigue failure of the 41-tooth bevel gear.

Safety action taken

Eurocopter has issued the following two alert service bulletins to check for the proper adjustment of the torque dampening system on Unison starter-generators installed on the Eurocopter fleet of aircraft:

  • AS 350 Alert Service Bulletin No. 80.00.07 Rev.0 dated 19 December 2008
  • EC 130 Alert Service Bulletin No. 80A003 Rev.0 dated 19 December 2008

In July 2008, Turbomeca issued Service Bulletins (SB) No. 292 72 0325 and No. 292 72 2090 regarding, respectively, TU 325 modification for Arriel 1 and TU 90 modification for Arriel 2 engines. According to Turbomeca, the aim of these modifications, which introduce a 41-tooth bevel gear with a thickened rim, was to improve the tolerance of the 41-tooth bevel gear to dynamic stress caused by high or excessive levels of electrical power tapped from the generator. The application of the SB was as follows:

  • systematic on the new engines for Sikorsky S76 and single-engine Eurocopter helicopters;
  • at the operators' request for engines in service; and
  • in case of replacement of the 41-tooth bevel gear during repair of module 01.

However, given the results of its investigations, Turbomeca has concluded that TU 90 and TU 325 do not resolve the last two occurrences of 41-tooth bevel gear failures or other situations where a starter-generator is installed with an incorrectly adjusted dampening system. Turbomeca can only confirm that the new design is at least as robust as the current design relative to abnormal vibration and torsional oscillation.

As well, the European Aviation Safety Agency has issued Airworthiness Directive (AD) 2009-0004 requiring mandatory compliance with the service bulletins.

TSB Final Report A08A0095—Engine Failure and Collision with Terrain

On July 14, 2008, a float-equipped de Havilland DHC-2 (Beaver) aircraft departed Crossroads Lake, N.L., at approximately 0:813 ADT with the pilot and six passengers on board. About three minutes after takeoff as the aircraft continued in the climb-out, the engine failed abruptly. When the engine failed, the aircraft was about 350 ft above ground with a ground speed of about 85 mph. The pilot initiated a left turn and, shortly after, the aircraft crashed in a bog. The pilot and four of the occupants were seriously injured; two occupants received minor injuries. The aircraft was substantially damaged, but there was no post-impact fire. The impact forces activated the onboard emergency locator transmitter.

de Havilland DHC-2 (Beaver) aircraft
The damaged aircraft after the accident

Findings as to causes and contributing factors

  1. The linkpin plugs had not been installed in the recently overhauled engine, causing inadequate lubrication to the linkpin bushings, increased heat, and eventually an abrupt engine failure.
  2. Immediately following the engine failure, while the pilot manoeuvred the aircraft for a forced landing, the aircraft entered an aerodynamic stall at a height from which recovery was not possible.

Finding as to risk

  1. The failure to utilize available shoulder harnesses increases the risk and severity of injury.

TSB Final Report A09C0017—Collision with Terrain at Takeoff

On February 4, 2009, a ski-equipped de Havilland DHC-6 Series 100 was taking off from a ski strip east of and parallel to Runway 36 at La Ronge, Sask. After the nose ski cleared the snow, the left wing rose and the aircraft veered to the right and the captain, who was the pilot flying, continued the takeoff. However, the right ski was still in contact with the snow. The aircraft became airborne briefly as it cleared a deep gully to the right of the runway. The aircraft remained in a steep right bank and the right wing contacted the snow-covered ground. The aircraft flew through a chain link fence and, at approximately 09:15 CST, crashed into trees surrounding the airport. The five passengers and two crew members evacuated the aircraft with minor injuries. There was a small fire near the right engine exhaust that was immediately extinguished by the crew.

A ski-equipped de Havilland DHC-6 Series 100

Findings as to causes and contributing factors

  1. Contamination on the wings of the aircraft was not fully removed before takeoff. It is likely that asymmetric contamination of the wings created a lift differential and a loss of lateral control.
  2. Although the operator was not authorized for short takeoff and landing (STOL) takeoff on this aircraft, the crew conducted a STOL takeoff, which reduced the aircraft's safety margin relative to its stalling speed and minimum control speed.
  3. As a result of the loss of lateral control, the slow STOL take-off speed, and the manipulation of the flaps, the aircraft did not remain airborne and veered right, colliding with obstacles beside the ski strip.

Findings as to risk

  1. The out-of-phase task requirements regarding the engine vibration isolator assembly, as listed in the operator's maintenance schedule approval, results in a less than thorough inspection requirement, increasing the likelihood of fatigue cracks remaining undetected.
  2. The right engine inboard and top engine mounts had pre-existing fatigue cracks, increasing the risk of catastrophic failure.

Other findings

  1. The cockpit voice recorder (CVR) contained audio of a previous flight and was not in operation during the occurrence flight. Minimum equipment list (MEL) procedures for logbook entries and placarding were not followed.
  2. The operator's safety management system (SMS) did not identify deviations from standard operating procedures.

Safety action taken

The operator has taken the following actions:

  • All DHC-6 engine mounts have been inspected.
  • The operator's inspection program has been amended to include the manufacturer's recommendation to overhaul or replace the engine mounts every 3 000 hr.
  • Short take-off and landing (STOL) procedures have been suspended.

TSB Final Report A09Q0181—Fuel Starvation

On October 11, 2009, a privately operated Piper PA-34-200T took off from Saint-Georges Airport, Que., and was headed for Gatineau, Que., on an instrument flight plan. The aircraft was in cruising flight at an altitude of 10 000 ft and was 7.4 NM southwest of Mirabel Airport, Que., when both engines simultaneously lost power. The aircraft entered a 180° right turn. The pilot informed air traffic control that he was having engine problems but did not declare an emergency. Radar vectoring was provided to the pilot to direct him to Mirabel Airport. During the descent, the aircraft deviated southward before turning back toward the airport. The aircraft had insufficient altitude to glide to the airport and crashed in a maple bush 1.2 NM from the threshold of Runway 06 at Mirabel Airport at 17:32 EDT. The aircraft was located by a helicopter several minutes later. The pilot, who was the sole occupant of the aircraft, was seriously injured.

Findings as to causes and contributing factors

  1. The right fuel selector was left in the XFEED position, probably because the pilot was distracted and/or failed to follow the checklist. As a result, both engines were being fuelled by the left tank until it was completely empty, causing both engines to stop simultaneously.
  2. The pilot relied on a fuel quantity indicator system that was based on the engine's fuel consumption and not on the quantity of fuel remaining indicated by the gauges.
  3. The pilot did not recognize the power loss as being a failure of both engines. The emergency checklist for engine failure was not completed.

Piper PA-34-200T

Other findings

  1. The aircraft's emergency locator transmitter (ELT) broadcast signals on 121.5 MHz and 406 MHz. The ELT was not damaged on impact, but its antenna was broken, making it difficult to capture signals.
  2. The pilot did not declare an emergency and did not clearly indicate the nature of the problem; therefore air traffic control (ATC) could not anticipate his needs.

TSB Final Report A10Q0070—Collision with Terrain

On May 19, 2010, the pilot rented a Cessna 172 for a 2-hour period from 14:00 to 16:00, for a pleasure flight under visual flight rules from Québec City/Jean-Lesage International Airport to L'Isle-aux-Grues, Que. The aircraft was carrying the pilot and three passengers. At approximately 15:18 EDT, the aircraft made a touch-and-go on Runway 25 at L'Isle-aux-Grues airport. On the climb-out, the aircraft halted its climb and started flying around the island at low altitude. At 15:22, a quarter of a mile south of the runway, the aircraft struck a pile of rocks and earth in a field, then crashed and caught fire. The aircraft was partly destroyed by fire. The four occupants died as a result of the accident. The emergency locator transmitter (ELT) activated on impact; satellites received a signal a few seconds after the accident and Canada Search and Rescue was notified.

History of the flight following the touch-and-go

The Cessna halted its climb shortly after its touch-and-go on Runway 25 and continued flying at low altitude. It disappeared behind the trees on the western tip of the island, then proceeded east along the south shore of the island about 200 ft above the ground. Abeam the airport, the aircraft turned left and headed northwest on a track perpendicular to the runway centre line. The aircraft overflew a small wood then descended to a few feet above a field. The aircraft flew just above the ground for a distance of 350 ft before striking a mound of rocks and earth. The aircraft partly broke up and continued in the air until it struck the terrain and caught fire. The final impact was in a field about 255 ft from the mound. The pilot and two passengers were fatally injured. The other passenger died in hospital a few hours later.

Low-altitude flight

Flying at low altitude can be dangerous: the field of view is more limited and the background landscape can conceal obstructions if it does not provide sufficient contrast. In this occurrence, the low-altitude flight was made over a non built-up area and, in large part, over water. Just before ground impact, the aircraft overflew a small wooded area at low altitude then descended to just above a cultivated field.

Section 602.14 of the Canadian Aviation Regulations (CARs) about low-altitude flight states, with regards to flight over a non built-up area:

Except where conducting a take-off, approach or landing or where permitted under section 602.15, no person shall operate an aircraft [...] at a distance less than 500 feet from any person, vessel, vehicle or structure.

Cessna 172

Analysis

The accident occurred because the aircraft, while flying just above the ground, struck a mound 8 ft in height. Due to a lack of evidence, the investigation was unable to determine why the pilot stopped the climb after the touch-and-go landing and continued flying at low altitude. Nor could it be determined why the aircraft descended to a few feet above terrain, which was unsuitable for landing, just before the initial impact.

Two hypotheses may explain why the pilot made a low-altitude flight which, resulted in a collision with the terrain.

Technical deficiency with the aircraft

It is possible that, after encountering mechanical trouble, the pilot was attempting to make an emergency landing when the aircraft struck the mound. The elements that support this hypothesis are:

  • the pilot was not known to fly at low altitude;
  • the marks on the engine tachometer dial indicate that the engine was running between 1 800 rpm and 1 900 rpm at the time of impact, which is below the normal cruise power level;
  • the pilot sent an unintelligible radio message shortly before the collision.

However, no mechanical deficiency which could have caused the engine to lose power or the aircraft to become uncontrollable in flight were noted or discovered prior to the flight or on examination of the aircraft. In fact, damage to the propeller indicates that the engine was producing power at the time of impact.

Based on the damage to the aircraft, the impact marks on the mound and the trajectory of the debris trail, the Cessna was configured for cruise flight and the pilot had control of the aircraft until the time of impact. The aircraft was flying at over 57 mph at the time of initial impact, the aircraft did not stall. The marks on the engine tachometer were made when the engine rpm decreased as a result of the propeller striking the ground.

Pleasure flight just above ground without intent to land

The aircraft occupants intended to land at L'Isle-aux-Grues airport for sightseeing. To that end, the pilot had rented the aircraft for 2 hr (from 14:00 to 16:00). But because the aircraft did not take off from Québec City until 14:47, it was impossible to make the stopover as planned and return on time. In fact, the pilot had less than 10 min to spend in the area before departing on the return leg. It is possible the pilot decided to overfly the island to give his passengers a view of the landscape from the air in lieu of stopping over; a low-altitude flight would have provided an exceptional view. None of these hypotheses could be proven with a degree of certainty.

It is likely the pilot was looking straight ahead while descending over the field. By extension, the pilot likely did not see the mound when the aircraft flared to level flight.

Finding as to causes and contributing factors

  1. For undetermined reasons, the aircraft was flying low, just above the ground, when it struck an 8-foot mound in a field and crashed.
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