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. 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 A04A0099-Collision with Terrain

On August 19, 2004, the pilots flew a Piper PA31-350 aircraft from Québec City, Que., to Saint John, N.B., on an IFR flight, with Fredericton, N.B., as their alternate airport. On arrival, they flew a radar-vectored, instrument landing system (ILS) approach in low-visibility conditions to Runway 23 at the Saint John airport. Radio contact was lost while the aircraft was on the approach, and a brief emergency locator transmitter (ELT) signal was heard at 22:34:30 Atlantic Daylight Time (ADT). The aircraft had crashed on final approach, and the two pilots sustained serious burn injuries in the ensuing post-crash fire.

TSB Final Report A04A0099 —Collision with Terrain

Findings as to causes and contributing factors

  1. Rather than conduct a missed approach when the approach became unstabilized, the crew continued in an attempt to land beyond the point where a missed approach could be executed, and the aircraft struck the terrain.
  2. The crew members most likely experienced a loss of situational awareness during the latter stages of the approach and, consequently, were unable to fly the aircraft on the required track and descent profile for a safe transition to landing.
  3. The crew members were permitted by regulation to conduct the approach in reported visibilities that were below the minimum advisory values published for the ILS approach, when they did not have procedures or training to operate as a crew in these conditions.

Finding as to risk

  1. The crew did not have the benefit of up-to-date, in-flight weather conditions or knowledge that a Beech 1900 had just carried out a missed approach on which to base their approach decisions.

TSB Final Report A05P0103-Tail-Rotor Strike (External Load)-Loss of Control

On May 7, 2005, a Messerschmitt-Bolkow-Blohm (MBB) BO 105 helicopter was carrying out external load operations near Bella Bella, B.C. It had completed 27 external loads and was returning to the Canadian Coast Guard Ship (CCGS) Bartlett from Dryad Point Lighthouse Station with an empty cargo bonnet. En route over the water, at an altitude of about 200 ft, the bonnet went above and behind the tail rotor, and the longline hung up on the back of the helicopter. The helicopter slowed, began to descend, turned right, and then crashed into the water. It sank immediately. The pilot was able to exit the sunken helicopter, but remained face down in the water. He was wearing an uninflated life jacket. The pilot was rescued within three minutes and revived, but remained in critical condition for several days. The helicopter was found at a depth of 26 m on an ocean floor slope.

Bonnet

Bonnet

Finding as to causes and contributing factors

  1. The rope used to snug the top of the bonnet most likely slid up the beckets, allowing the bonnet to open and fly into the flight path of the helicopter, carrying the longline with it. The longline came into contact with the tail rotor and disabled it, rendering the helicopter uncontrollable.

Bonnet with sling attachment

Bonnet with sling attachment

Findings as to risk

  1. Most helicopters are not designed or certified to accommodate vertical reference external load operations; however, these operations are very common and pilots fly in this higher-risk environment without proper safety-restraint devices.
  2. It is likely that the pilot's unrestrained upper body moved around the cabin at impact. This increased the risk of injury and, in this case, the risk of drowning.
  3. Even when properly secured, persons in either front seat risk hitting their heads on a fixture to which the life raft is normally secured.
  4. The colour of the pilot's helmet, life-vest cover and flight suit (grey and navy blue, respectively) made it difficult to see him in the ocean, increasing the risk of him not being found and rescued.

Other finding

  1. The pilot's helmet protected his head from severe injury, allowing him to extricate himself from the sunken wreckage.

Safety action taken

Operator

On May 9, 2005, the operator issued a safety notice, restricting operations with empty or light external sling loads.

On May 25, 2005, the operator produced draft standard operating procedures (SOPs) for helicopter external load operations. These SOPs restrict the use of bonnets and caution pilots about light and unstable loads.

Transportation Safety Board of Canada (TSB)

On May 31, 2005, the TSB sent a Safety Information Letter to Transport Canada (TC), outlining the facts of this accident that showed that, despite the Canadian Aviation Regulations (CARs) and the previous Safety Advisory to TC (A010006), helicopter slinging operations without upper-body restraint continue.

In response to the above-noted Letter, TC provided the following:

  • If the upper-body restraint equipment is used properly, and in accordance with the CARs, it will provide the protection intended by those requirements.
  • If an operator discovers that installed equipment, a shoulder harness in this case, is unsuitable for "vertical reference helicopter sling operations," then TC has a well-established process in place for assessing and approving supplemental aircraft equipment.
  • It is the responsibility of the industry to comply with the regulations, and, if warranted, apply for an approval of a configuration to meet the industry's operational needs. TC continues to welcome air operator and manufacturer initiatives to promote safe helicopter external load operations.
  • Notwithstanding the current regulations and industry initiatives undertaken to date, TC has initiated the process to conduct research and development on the issue. A proposal has been submitted to the Civil Aviation Research and Development Committee to study crew restraint in vertical reference external load (VREL) operations. The objective is to develop a new restraint system and produce a safety education and promotion product on VREL operations.

On May 31, 2005, the TSB sent a Safety Advisory to TC, indicating that, during this investigation, a test revealed that, even when properly restrained, persons seated in either of the front seats are able to hit their heads on a fixture installed to hold a liferaft. The advisory suggested that TC may wish to modify the fixtures that hold the liferafts in the MBB BO 105 helicopters to remove the hazard, or limit use of the front seats to persons wearing protective head gear. It also suggested that TC may wish to verify that other aircraft have not been modified to induce similar hazards.

In response to the above-noted Safety Advisory, TC provided the following:

  • TC is undertaking a complete review of the applicable limited supplemental type certificate (LSTC) data package with regards to this occurrence. The data used to show compliance with section 27.561 of the U.S. Federal Aviation Regulations (FARs) are being reviewed and a determination will be made as to whether a design change is required. Although the review is not yet complete, it is possible that padding could be added to the fixture and a requirement be made that helmets are to be worn with this installation.

On June 1, 2005, the TSB sent a Safety Information Letter to TC, highlighting the facts of this accident and the continued operational practices of helicopters carrying empty or light slings. The letter pointed out that the TSB had made a recommendation (A93-12) to TC in 1993, that it coordinate the development and implementation of airworthiness standards and operational limitations for helicopter slinging equipment.

In response to the above-noted Letter, TC provided the following:

  • Chapter 527.865 of the CARs addresses external loads for normal category helicopters and Chapter 529.865 of the CARs deals with transport category helicopters. These standards state the certification basis for helicopters equipped with external slinging capabilities (cargo hook). Helicopter slinging equipment is considered part of the load rather than the helicopter; therefore, it is not subjected to a Technical Standard Order (TSO) or supplemental type certificate (STC) approval process.
  • The responsibility for ensuring safe slinging operations remains with the operator, and specific information on slinging and crew training is to be contained in the company operations manual. TC continues to welcome air operator and manufacturer initiatives to promote safe helicopter external load operations.
  • Strategies to address helicopter rotor/sling strikes, and unsafe equipment and practices that lead to them, have included numerous articles in TC's safety publications, such as the former Aviation Safety Vortex newsletter.
  • TC continues to be concerned with this area of operations. The Department has produced a new safety awareness video, titled "Keep Your Eyes on the Hook! Helicopter External Load Operations-Ground Crew Safety." The video's intended audience is ground crew and it addresses subjects such as occupational safety and health issues, briefings, protective equipment, communications and checking load and equipment such as straps and bonnets.

This article in the Aviation Safety Letter will further promote awareness of this hazardous practice.

TSB Final Report A05O0225-Controlled Flight Into Terrain (CFIT)

On September 30, 2005, a Piper PA31 Navajo aircraft departed Runway 25 at Kashechewan, Ont., at approximately 21:30 Eastern Daylight Time (EDT) on a night VFR flight to Moosonee, Ont., 72 NM to the southeast. The captain was the pilot flying and was seated in the left seat. The aircraft became airborne approximately halfway down the runway, and the flight crew lost sight of the runway lights and any visual reference to the ground shortly after takeoff. The captain selected the landing gear up, and, at 200 ft above ground level (AGL), the first officer selected the flaps up, after which the captain set climb power. There was a slight drop in manifold pressure on the left engine, and the captain was readjusting the power when the aircraft struck the ground. The aircraft bounced into the air and came to rest approximately 300 m past the departure end of the runway. The aircraft was substantially damaged by impact forces. The six passengers and two pilots were not injured.

TSB Final Report A05O0225 —Controlled Flight Into Terrain (CFIT)

Findings as to causes and contributing factors

  1. The flight crew did not follow the operator's standard operating procedures (SOPs) and ensure that a positive rate of climb was maintained after takeoff. The aircraft developed an undetected sink rate and struck the ground.
  2. During the night VFR departure into "black hole" conditions, the flight crew likely experienced a somatogravic illusion, giving them a false climb sensation. This likely contributed to the captain allowing the aircraft to descend into the ground.

Findings as to risk

  1. The operator was using a maximum take-off weight (MTOW) of 6 840 lbs, when the actual MTOW was 6 730 lbs.
  2. Tie-down rings and cargo restraints were not installed in the aircraft. The baggage that was loaded inside the aircraft was not secured, resulting in it being strewn about the rear of the cabin during the crash sequence.
  3. A pre-flight passenger briefing was not conducted, and the passengers were unfamiliar with the operation of the aircraft exit.

Other findings

  1. A scale was carried on board the aircraft but was not used. Because the flight crew estimated the baggage weight, the actual weight of the baggage was undetermined.
  2. The total weight of the passengers, using self-reported weights, exceeded the standard weights by approximately 135 lbs.
  3. The MTOW of the aircraft was incorrectly documented during two Transport Canada audits.

TSB Final Report A05P0269-In-Flight Break-Up

TSB Final Report A05P0269—In-Flight Break-Up

On November 3, 2005, a Boeing Vertol helicopter, model BV-107 II, was engaged in helicopter logging operations in the South Bentinck Arm, 20 NM from Bella Coola, B.C. At 13:30 Pacific Standard Time (PST), the helicopter was returning to the log pick-up site when one of the two pilots radioed that the helicopter was vibrating. Moments later, the crew made a second radio transmission indicating that the helicopter was behaving in an unusual manner, and that they would be returning to the maintenance base. Approximately 10 seconds later, the helicopter suffered an in-flight break-up and fell to the ground in several sections. Both crew members sustained fatal injuries.

Findings as to causes and contributing factors

  1. The limit switches from the occurrence actuator did not meet the manufacturer's specification for switch arm travel. Since the switches cannot move in the vertical axis, it is likely that the greater arm travel distance prevented activation of the retract limit switch.
  2. The retract limit switch's failure to activate caused the end fitting adapter to be driven into the face of the torsion bar, imposing a tensile load on the jack screw nut of over 1 300 lbs.
  3. This high tensile load created a stress concentration within the 0.001-in. thread-root radius that was higher than the jack screw nut material endurance limit, which in turn caused the jack screw nut to fail.
  4. The aft rotor blades became unstable following failure of the speed trim actuator jack screw nut. The aft rotor blades tilted forward into the helicopter fuselage, causing an in-flight break-up.

Findings as to risk

  1. There are no indications to the pilots that the speed trim actuator has contacted the mechanical stop. Pilots could continue to unknowingly operate a speed trim actuator against the mechanical stop, eventually resulting in failure of the jack screw nut and a catastrophic airframe failure.
  2. An internal thread-root radius of the jack screw nut was not specified in the production drawings. A larger thread-root radius would likely have a significant beneficial effect on fatigue life.
  3. Once the speed trim actuator is installed and adjusted, no further periodic maintenance is required. Failure of either the retract or the extend limit switches would likely go undetected until the next overhaul interval.
  4. Since the fatigue originated from the internal threads, fatigue cracking of the jack screw nut would not be apparent during visual inspections of the speed trim actuator. Internal fatigue cracks would continue to grow until failure occurred.
  5. The arm of the switch is subject to wear, increasing the likelihood of a switch malfunction.
  6. The operator could not provide source control documents for the parts replaced during the last overhaul of the speed trim actuator. Proper documentation aids in identifying the manufacturer and location of defective or unapproved components.

Other finding

  1. The illustrated parts catalogue (IPC) for the speed trim actuator did not reflect the interchangeability of the USML117 and the 2LML82E switches.

Safety action taken

On November 23, 2005, the operator issued an inter‎office memorandum to all Boeing 107 helicopter crews, detailing recurrent procedures to check the operation and serviceability of the speed trim actuator switches. As a result of this memorandum, one other speed trim actuator was identified as having a non-functional extend limit switch.

On November 23, 2005, Boeing Aerospace Support in Philadelphia issued Service Bulletin (SB) 107-67-1001, requesting that all operators of Model 107 helicopters (BV and KV) and 107 derivatives inspect and functionally test the longitudinal cyclic trim actuator limit switches. Boeing recommended that this test be accomplished before the next flight, and before each subsequent flight until further notice.

TSB Final Report A05O0257 -Runway Overrun

On November 15, 2005, a Gulfstream 100 was conducting an IFR flight from West Palm Beach, Fla., to Hamilton, Ont., with two pilots on board. The co-pilot was seated in the left seat and was the pilot flying. Approaching the destination, the flight was cleared for the instrument landing system (ILS) approach to Runway 12 at the Hamilton airport. The approach was at night in instrument meteorological conditions (IMC). At 400 ft to 500 ft above ground level (AGL), the flight crew saw the runway. At approximately 19:02 Eastern Standard Time (EST), the aircraft touched down on the wet runway with about 3 000 ft of runway remaining. The flight crew used all available braking systems to slow the aircraft. However, it ran off the end of the runway and travelled 122 ft downslope before it came to an abrupt stop when the nose wheel sheared off. The aircraft sustained substantial damage, but neither flight crew member was injured during the runway excursion. The emergency locator transmitter (ELT) activated, and the aircraft rescue and firefighting (ARFF) teams responded.

Aircraft being prepared to be towed back onto the runway

Aircraft being prepared to be towed back onto the runway

Findings as to causes and contributing factors

  1. The pilot flying was slow to reduce the power to idle after flaring the aircraft for landing. Due to the excess airspeed and power, the aircraft floated, touching down with approximately 3 000 ft of runway remaining.
  2. Although the available 3 000 ft of runway remaining exceeded the unfactored estimated ground roll of 2 200 ft, the aircraft was unable to stop. A touchdown speed higher than the landing reference speed (Vref), slow deployment of the thrust reversers, standing water at the intersection of the runways, friction values at the runway ends that were at or below the Transport Canada runway maintenance planning level, and limited tire tread depth likely contributed to the runway excursion.
  3. During the landing roll, the aircraft's tires hydroplaned, reducing the braking forces.

TSB Final Report A06W0002 -In-Flight Engine Fire

On January 5, 2006, a Douglas C-54G-DC (DC‎4) departed from Norman Wells, N.W.T., at 17:49 Mountain Standard Time (MST) for a VFR flight to Yellowknife, N.W.T., with a crew of four and 2 000 lbs of cargo. While climbing through an altitude of approximately 3 500 ft above sea level (ASL), the crew experienced a failure of the No. 2 engine and a nacelle fire. The crew carried out the engine fire checklist, which included discharging the fire bottles and feathering the No. 2 propeller. The fire continued unabated. During this period, an uncommanded feathering of the No. 1 propeller and an uncommanded extension of the main landing gear occurred. The crew planned for an emergency off-field landing, but during the descent to the landing area, the fuel selector was turned off as part of the engine securing checklist, and the fire self-extinguished. A decision was made to return to the Norman Wells airport where a successful two-engine landing was completed at 18:04 MST. The aircraft sustained substantial fire damage, but there were no injuries to the four crew members on board.

Findings as to causes and contributing factors

  1. Airworthiness Directive (AD) 48-12-01 mandates the replacement of the potentially hazardous fuel line, but the line had not been replaced on this aircraft.
  2. A fuel leak from the main fuel inlet line in the engine compartment of this cargo DC-4 caused an in-flight fire that spread into the nacelle and wing.
  3. The fuel-fed fire burned for an extended period of time because turning the fuel selector off is not required as part of the primary engine fire checklist.

Safety action taken

The Transportation Safety Board of Canada (TSB) issued two Aviation Safety Information Letters to Transport Canada (TC), addressing the following concerns in this occurrence:

  • Aviation Safety Information Letter A060003‎1 (A06W0002)-Emergency Checklist-Engine Fire Procedure for Douglas C54G-DC Aircraft, was sent to TC on February 23, 2006. This Letter highlighted the concern regarding the checklist timing for the fuel selector valve shutoff.

The operator has amended the engine fire checklist and the standard operating procedures (SOPs) for engine fire in the air, with the addition of "fuel selectors off" immediately after "mixtures to idle cut off."

  • Aviation Safety Information Letter A060005‎1 (A06W0002)-Fuel Line Installation Configuration and Maintenance, was sent to TC on March 2, 2006. This Letter addressed the concern regarding the applicability of AD 48-12-01 to C-54G-DC cargo aircraft.

On June 6, 2006, TC sent a response regarding Aviation Safety Information Letter A060005-1 (A06W0002) to the TSB. TC indicated that it had contacted the only operator of this aircraft type in Canada to determine if AD 48-12-01 had been incorporated on its aircraft. Two of its four aircraft were found not in compliance with the subject AD, and the company initiated the necessary steps to correct this.

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