A05C0187 - Cessna 208 Operation into Icing Conditions
Background
On 06 October 2005, a Cessna 208B, registration C-FEXS, operated by Morningstar Air Express as Flight MAL8060, departed Winnipeg, Manitoba, at 0537 central daylight time on an instrument flight rules (IFR) freight flight to Thunder Bay, Ontario. The aircraft, with one pilot and about 2470 pounds of cargo on board, departed Runway 36, climbed, and turned right on course. About 4.5 nautical miles (nm) southeast of the airport, the pilot requested an immediate return to the airport due to icing considerations, but did not declare an emergency. Departure control provided an initial radar vector to Runway 31, and the aircraft turned to a southwesterly heading. A second vector was provided and the pilot responded; however, the aircraft did not turn and descended below radar coverage. The aircraft departed controlled flight and crashed on railway property in the city of Winnipeg. The pilot was fatally injured. The aircraft was destroyed by impact forces and a post-impact fire. The accident occurred during hours of darkness at 0543. The investigation (A05C0187) is ongoing.
Recommendations
Although the manufacturer has taken action to provide procedures for the operation of the Cessna 208 aircraft type in icing conditions, pilots continue to experience difficulty in maintaining control of the aircraft and exiting those conditions as specified in the aircraft flight manual (AFM). Although the aircraft is approved for flight into moderate icing conditions, continuing occurrence experience and the manufacturer's data indicate that the aircraft may not be able to safely operate in those conditions or to safely exit those conditions as specified in the AFM. Therefore, the Board recommends that:
The Department of Transport require that Canadian Cessna 208 operators maintain a minimum operating airspeed of 120 knots during icing conditions and exit icing conditions as soon as performance degradations prevent the aircraft from maintaining 120 knots. A06-02
Transport Canada Response
On January 24, 2006, Transport Canada issued Service Difficulty Alert 2006-01. Service Difficulty Alert 2006-01R1 was released on February 1, 2006 and the latest revision 2006-01R2 was released on March 24, 2006. Copies of these three Alerts are attached.
Transport Canada also reviewed FAA AD 2006-06-06. The Department supports the FAA determination that these actions are necessary for safe operation. FAA AD 2006-06-06 has been accepted and is mandatory in Canada.
The manufacturer's data (Appendix 4) and historical data from the reviewed occurrences above indicate that the aircraft's stall speed can increase substantially in icing conditions due to residual ice on the aircraft, combined with the effects of the operation of the de-icing equipment. Although the manufacturer has set a minimum operating airspeed in icing conditions, the Board is concerned that the recommended 105 knots is not sufficient to provide an adequate stall warning threshold. Although the Cessna POH Supplement S1, Revision 7, dated 27 June 2005, recommends exiting icing conditions when the airspeed falls below 120 knots, it does not specify 120 knots as the minimum airspeed in icing conditions. Therefore, the Board recommends that:
The Department of Transport require that Canadian Cessna 208 operators maintain a minimum operating airspeed of 120 knots during icing conditions and exit icing conditions as soon as performance degradations prevent the aircraft from maintaining 120 knots. A06-02
Transport Canada Response
TC agrees with recommendation A06-02. TC reviewed FAA AD 2006-06-06, accepted the AD and it is now mandatory in Canada.
A05F0047 - Airbus Composite Rudder Inspection Program
Background
On 06 March 2005, an Airbus A310-300, serial number 597, registration C-GPAT, operated by Air Transat as Flight 961, departed Juan G. Gomez International Airport in Varadero, Cuba, for Québec/Jean Lesage International Airport, Quebec, with 2 pilots, 7 flight attendants, and 262 passengers on board. While at an altitude of 35 000 feet, the flight crew heard a loud bang followed by vibrations that lasted a few seconds. The aircraft entered a repetitive rolling motion, known as dutch roll, which decreased as the aircraft descended to a lower altitude. Once the aircraft reached about 19 000 feet, the flight crew had no indication of any abnormalities. The flight returned to Varadero where an uneventful landing was carried out. The Transportation Safety Board of Canada (TSB) investigation (A05F0047) into this occurrence is ongoing.
On arrival at Varadero, it was discovered that the aircraft rudder was missing. The rudder is made of composite sandwich construction, consisting of a nomex honeycomb core with carbon fibre face sheets. It had separated from the aircraft except for its bottom closing rib and the length of spar between the rib and the hydraulic actuators. Only small residual amounts of rudder side panel remained attached. An examination of the vertical tail fin of the aircraft, to which the rudder is attached, determined that the two rearmost fin attachment lugs were delaminated, likely the result of stresses that existed during the rudder separation.
The TSB investigation into this occurrence is being supported by the Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile (BEA) of France, the National Transportation Safety Board (NTSB) of the United States, and the Federal Bureau of Aircraft Accidents Investigation (BFU) of Germany. Technical advisors from Transport Canada, the Federal Aviation Administration (FAA), Airbus, and Air Transat are also participating.
Recommendations
The separation of the rudder from Air Transat Flight 961 and the damage found during the post-occurrence fleet inspections suggest that the current inspection program for Airbus composite rudders may not be adequate to provide for the timely detection of defects. In addition, the recent discovery that disbonds could grow undetected and the increasing age of the composite rudders suggest that increased attention is warranted to mitigate the risk of additional rudder structural failures. The consequences of a rudder separation include reduced directional control and possible separation of the vertical tail plane.
Therefore, the Board recommends that:
The Department of Transport, in coordination with other involved regulatory authorities and industry, urgently develop and implement an inspection program that will allow early and consistent detection of damage to the rudder assembly of aircraft equipped with part number A55471500 series rudders. A06-05
Transport Canada Response
Transport Canada concurs with the TSB suggestion that the current A310-300 inspection program may not be adequate to provide timely detection of defects to the rudder assembly. This may be caused by either inappropriate inspection intervals or inadequate inspection techniques.
Background
At the time of this occurrence, composite materials in general were from a maintenance perspective, believed to have a no damage growth design philosophy. It was also believed that from a fatigue point of view, more frequent inspections of composite materials would not prove to be more effective. In addition, these concepts were an Industry accepted philosophy during the development of maintenance programs using the Maintenance Review Board (MRB) process.
Safety Action
As a result of this occurrence, and the additional findings based on the Airbus All Operators Telex, Transport Canada now believes that there is potential for damage growth. Following this determination, the Department inspected additional Canadian registered A310-300 series aircraft in order to evaluate the effectiveness of the current Airbus maintenance program.
The following corrective actions are currently being taken by Transport Canada:
Short Term Action
Transport Canada will send a letter to Airbus Industries and the DGAC of France detailing the results of our additional inspection on a Canadian registered A310-300 series aircraft.
Transport Canada will recommend that a detailed inspection of the drainage path of the rudder for blockage be added to the current inspection program to insure that there is adequate drainage.
Transport Canada will request that Airbus Industries review the current inspection program for the vertical stabilizer and rudder assembly for the A300/A310 aircraft series.
Long Term Action
Since a tap test, a scheduled inspection of the rudder required at the time of the occurrence, is potentially not effective in determining smaller areas of delamination or disbond of composite materials, Transport Canada is currently working with the National Research Council of Canada to identify suitable inspection techniques that will detect failures in composite materials.
To better identify failures in composite material, Transport Canada will coordinate with the International MRB Policy Board to review the logic used in developing maintenance programs.
Transport Canada believes the results of this effort will have a wide impact on all FAR 25 aircraft currently being produced globally.
The concern regarding the safety of affected aircraft is such that the BEA of France has recently issued a similar recommendation. As well, the NTSB is contemplating similar recommendations based on its investigation into the FedEx occurrence.
Airbus Composite Rudder Inspection Program
As the investigation continues, the Board may make further safety recommendations should additional safety deficiencies be identified at existed during the rudder separation.
A04H0004 - Reduced Power at Take-off and Collision
Synopsis
On 14 October 2004, an MK Airlines Limited Boeing 747-244SF (registration 9G-MKJ, serial number 22170) was being operated as a non-scheduled international cargo flight from Halifax, Nova Scotia, to Zaragoza, Spain. At about 0654 coordinated universal time, 0354 Atlantic daylight time, MK Airlines Limited Flight 1602 attempted to take off from Runway 24 at the Halifax International Airport. The aircraft overshot the end of the runway for a distance of 825 feet, became airborne for 325 feet, then struck an earthen berm. The aircraft's tail section broke away from the fuselage, and the aircraft remained in the air for another 1200 feet before it struck terrain and burst into flames. The aircraft was destroyed by impact forces and a severe post-crash fire. All seven crew members suffered fatal injuries.
Safety Action Taken
Safety Advisory A040058-1
On 20 October 2004, the Transportation Safety Board of Canada (TSB) issued Safety Advisory A040058-1(Verification of Cargo Weights) to Transport Canada (TC). The Safety Advisory indicated that TC might wish to examine the adequacy of cargo handling procedures, both inside and outside Canada, and, in particular, the adequacy of load weight verification and the regulatory oversight of these issues.
On 09 December 2004, TC responded to Safety Advisory A040058-1. The letter quoted several regulations applicable to commercial operations: International Civil Aviation Organization (ICAO) standards and recommended practices, Canadian Aviation Regulations, Joint Aviation Requirements (JARs), and Federal Aviation Regulations (FARs). TC stated that the intent of the regulations is to ensure that the actual weight of the cargo, including the weight of the contents, the packing material, the packaging, the pallet or unit load device, the strapping, the wrapping, and any other device or material being transported with the cargo is accounted for in the total weight of the cargo. TC further stated that the regulations clearly indicate that it is an operator's responsibility to ensure that proper weighing procedures are in place to support its operations.
It is TC's position that the existing regulations and standards adequately address the issues raised in the Safety Advisory. However, in light of the recent accident in Halifax, Nova Scotia, and to reinforce the absolute necessity for accurate load control, TC published a Commercial and Business Aviation Advisory Circular on this issue on 04 June 2005.
Safety Advisory A040059-1
On 22 October 2004, the TSB issued Safety Advisory A040059-1 (Runway Slope Information - Publication Errors) to TC. The Safety Advisory raised a concern about the accuracy of published runway slope information. The slope datum for Runway 24 at Halifax International Airport published in Canadian aeronautical information publications was incorrectly depicted as 0.17 per cent down, when it should have read 0.17 per cent up. The Safety Advisory suggested that TC might wish to ensure that similar runway slope information errors do not exist for other aerodromes. A review of quality assurance measures regarding the provision and depiction of aerodrome information in Canadian flight information publications was suggested.
On 09 December 2004, TC responded to Safety Advisory A040059-1. TC indicated that a preliminary review has not uncovered further errors in published runway slope data. The error in the Halifax data is the result of a human transposition error. The error in the slope value for Runway 24 was discovered in the course of this accident investigation. TC was advised of the error, and a NOTAM (Notice to Airmen) was issued instructing holders of the Canada Air Pilot to delete the slope information for all runways at the Halifax International Airport.
Subsequently, it was discovered that, in accordance with NAV CANADA's Aeronautical Information Publication (A.I.P. Canada) specifications, only slope values greater than 0.3 per cent are published. Therefore, a second NOTAM was issued, instructing holders of the applicable documents to re-insert the slope value for Runway 33, and delete the value for Runway 24.
Additionally, as a result of this Safety Advisory, an Aerodrome Safety Urgent Bulletin was sent to TC regional offices for distribution to all airports and registered aerodromes. The Urgent Bulletin reminds all airport/aerodrome operators of their responsibility to verify the accuracy of all published data, and to report immediately, via a NOTAM, the corrections to be made to aeronautical information publications. Direction concerning the methodology for the calculation of runway slope data is being reviewed and coordinated with NAV CANADA and other interested stakeholders.
NAV CANADA subsequently advised the TSB that, between 01 January 2004 and 01 October 2004, only two requests were received to amend runway slope information contained in its aeronautical information publications. After the issue of Safety Advisory A040059-1 and up to 01 December 2005, NAV CANADA had received a total of 73 requests to amend or to add runway slope information.
For further safety action taken, please see the TSB's report Section 4.0 - Safety Action Taken Section
TSB's report Section 4.0 - Safety Action Taken Section
Safety Action Required
Take-off Performance Monitoring System
In this accident, the take-off was attempted using a thrust setting and take-off speeds significantly lower than those required to become safely airborne. The company's standard call for "Set MAX POWER" during every take-off would not have provided any additional opportunity to inform the crew if the power being set was maximum or reduced. Once the take off began, the flight crew did not recognize that the aircraft's performance was significantly less than the scheduled performance until they were beyond the point where the take-off could be safely conducted or safely abandoned.
Several similar accidents and incidents have shown that there have been other crews throughout the aviation industry that have also not recognized inadequate take-off performance. Some of these occurrences have resulted in substantial aircraft damage and, in several accidents, substantial loss of life. Although several efforts have been undertaken to develop procedural and technical solutions that would alert crews to inadequate aircraft acceleration performance during take-off, these efforts still have not resulted in a reliable methodology or system being introduced and/or installed in transport category aircraft. Without such a system, there continues to be an unacceptable level of risk to crews and the travelling public.
Therefore, the Board recommends that:
The Department of Transport, in conjunction with the International Civil Aviation Organization, the Federal Aviation Administration, the European Aviation Safety Agency, and other regulatory organizations, establish a requirement for transport category aircraft to be equipped with a take-off performance monitoring system that would provide flight crews with an accurate and timely indication of inadequate take-off performance. A06-07
Transport Canada Response to Recommendation A06-07
It is agreed that if a Take-off Performance Monitoring System could be designed to function as intended, it could provide a significant safety benefit, however in order for Civil Aviation Authorities to establish a requirement for aircraft to be equipped with a take-off performance monitoring system, an acceptable system would have to exist. Transport Canada is not aware of any certified system that is available at this time to meet this recommendation.
A system that did not function correctly could create a greater hazard than the one it is supposed to protect against, in particular, a malfunctioning take-off performance monitoring system could cause crews to perform unnecessary high-speed rejected take-offs.
Although such systems have been under discussion for many years, none has yet been certified, nor as far as the Department is aware, offered for certification, because there are difficult technical problems associated with designing such a system. In order to be certified, the system would have to demonstrate a very high probability of providing correct information under all foreseeable operating conditions such as aircraft weight, altitude, temperature, wind, runway surface condition, aircraft configuration, and any other significant variable.
Although it is conceivable that such a system could be designed with current technology, a significant effort would be required by private industry and researchers to establish appropriate design criteria, detailed design and system development and then significant testing to ensure high reliability before acceptance. In addition, design criteria and standards would also require harmonisation with other Civil Aviation Authorities.
At present Transport Canada cannot establish a requirement for aircraft to be equipped with a take-off performance monitoring system but will revisit this issue when a certifiable product is developed.
Safety Issues Investigation Report SII A05-01 - Post-Impact Fires Resulting from Small-Aircraft Accidents
Executive Summary
Introduction
For aircraft with a maximum certified take-off weight of 5700 kilograms (12 566 pounds) or less, post-impact fire (PIF) contributes significantly to injuries and fatalities in accidents that are otherwise potentially survivable. A potentially survivable accident is one in which the impact forces are within the limits of occupant tolerance, the aircraft structure preserves the required survival space, and the occupant restraint is adequate.
This investigation examined Transportation Safety Board of Canada (TSB) data and the history of PIF safety action to become more informed and to provide discussion material with the intent of mitigating risks surrounding PIF in small aircraft, specifically regarding design certification. The historical incidence of PIF occurrences in aircraft weighing less that 5700 kilograms demonstrates a high probability of future similar occurrences, resulting in adverse human consequences, if current design standards are not addressed.
Statement of the Problem
PIF continues to contribute to injuries and fatalities in otherwise survivable accidents involving small aircraft. Both the National Transportation Safety Board (NTSB) and the Federal Aviation Administration (FAA) of the United States have attempted to address this issue through special studies and Notices of Proposed Rule Making.
In 1994, amendments to the United States Federal Aviation Regulations (FARs) introduced comprehensive fuel system crash resistance certification standards for normal and transport category helicopters to minimize the hazard of fuel fires to occupants following otherwise survivable impacts. Technology and design concepts intended to reduce the incidence of PIF have been demonstrated to be effective in helicopter, race car, and automotive applications. However, there is no requirement to incorporate these countermeasures into new or existing small aeroplane types or into small helicopters certified before November 1994.
Safety Action - Recommendations
Fire or smoke inhalation were identified as either partly or solely the cause of death for 205 (nearly 30 per cent) of the 728 fatalities and 80 (nearly 35 per cent) of the 231 serious injuries that occurred in the 521 accidents identified from the Aviation Safety Information System (ASIS) database as involving post-impact fire (PIF). This supports the concern that there is a significant risk for PIF and PIF-related injuries and fatalities in small-aircraft accidents, and that regulators should reconsider ways to reduce the risk and consequences of impact-induced fire in otherwise survivable accidents. While the design principles for crashworthy fuel systems are well known, at present, there are no airworthiness standards that require enhanced technical countermeasures to be fitted to small aircraft to reduce the incidence of PIF in circumstances other than gear-up landings.
PIF and fire-related injuries and fatalities can be mitigated through aircraft design, so as to prevent damage-induced ignition, preserve fuel system integrity, and reduce impact-related injuries in crash conditions. These design concepts, which have been shown to reduce the risk of fire and save lives in the helicopter and automotive industries, could be effectively applied to type-certificated small aircraft and to helicopters certified before November 1994 through improved regulatory standards.
The amateur-built aircraft and ultralight communities could benefit from the dissemination of safety information relevant to PIF risks and defences.
Considering the propensity for rapid propagation and the catastrophic consequences of fuel-fed PIF, the most effective defence against PIF is to prevent the fire from occurring at impact, either by eliminating sources of ignition or by containing fuel sufficiently to prevent contact with ignition sources, or both.
The following recommendations are made to address the safety deficiencies related to common unsafe conditions that contribute to the development of PIF and to fire-related injuries and fatalities, as identified by this investigation. The recommendations apply in general to small production aeroplanes, and where applicable, to small helicopters certified before November 1994. Transport Canada and the Federal Aviation Administration (FAA) may wish to communicate concerns and recommendations regarding PIF to the European Aviation Safety Agency (EASA) and other foreign airworthiness authorities in foreign states of manufacture.
Recommendation Regarding Value of Statistical Life
The report submitted to the TSB on the process of economic analysis into risk control options for mitigation of PIF risks identified that the U.S. guidelines on economic analysis and cost-benefit analysis (CBA) are commendable; however, the $3 million value of statistical life (VSL) figure currently used by the Department of Transportation and the FAA is low relative to recent empirical estimates. The original CBA for Notice of Proposed Rule Making (NPRM) 85-7A used a VSL of $1 million. Because numerous cost-effective technological advances to eliminate PIF have been developed, and given that benefits are directly proportional to the value chosen for VSL and to the effectiveness rate of the PIF risk control measures, the calculated benefits may be greater and the costs proportionately lower if recent higher empirical VSLs were applied to the original CBA. Using the comprehensive PIF database assembled during this investigation, it is possible to calculate the expected benefits in lives saved by preventing PIF. Using Canadian PIF statistics, the expected present-discounted benefits over the lifetime of an aircraft are several thousand U.S. dollars, and that value is sufficiently large that a detailed CBA may be warranted for specific PIF risk control option technologies (Lindsey and West, 2003). Therefore, the Board recommends that:
Transport Canada, together with the Federal Aviation Administration and other foreign regulators, revise the cost-benefit analysis for Notice of Proposed Rule Making 85-7A using Canadian post-impact fire statistics and current value of statistical life rates, and with consideration to the newest advances in post-impact fire prevention technology. A06-08
Recommendation Regarding Design Standards for New Aeroplanes
Aircraft design is fundamentally important to preventing PIF in impact-survivable accidents. There are currently no design standards that specifically address countermeasures to reduce the incidence of PIF in impact-survivable accidents involving newly manufactured small, production aeroplanes, other than during gear-up landings; therefore, occupants remain at risk of fire-related injury and fatality in accidents involving new aeroplane models. There are numerous engineering concepts and products that are known to eliminate potential ignition sources and protect against impact-induced fuel spillage in impact-survivable accidents. Requirements to consider and adapt these countermeasures in new aeroplane designs may significantly reduce the risk and incidence of PIFs in impact-survivable accidents. Therefore, the Board recommends that:
To reduce the number of post-impact fires in impact-survivable accidents involving new production aeroplanes weighing less than 5700 kg, Transport Canada, the Federal Aviation Administration, and other foreign regulators include in new aeroplane type design standards:
- methods to reduce the risk of hot items becoming ignition sources;
- technology designed to inert the battery and electrical systems at impact to eliminate high-temperature electrical arcing as a potential ignition source;
- requirements for protective or sacrificial insulating materials in locations that are vulnerable to friction heating and sparking during accidents to eliminate friction sparking as a potential ignition source;
- requirements for fuel system crashworthiness;
- requirements for fuel tanks to be located as far as possible from the occupied areas of the aircraft and for fuel lines to be routed outside the occupied areas of the aircraft to increase the distance between the occupants and the fuel; and
- improved standards for exits, restraint systems, and seats to enhance survivability and opportunities for occupant escape. A06-09
Recommendation Regarding Existing Production Aircraft
There are a large number of small aircraft already in service and the defences against PIF in impact-survivable accidents involving these aircraft are and will remain inadequate unless countermeasures are introduced to reduce the risk. The most effective ways to prevent PIF in accidents involving existing small aircraft are to eliminate potential ignition sources, such as hot items, high-temperature electrical arcing and friction sparking, and prevent fuel spillage by preserving fuel system integrity in survivable crash conditions. Technology that is known to reduce the incidence of PIF by preventing ignition and containing fuel in crash conditions may be selectively retrofitted to existing small aircraft, including helicopters certified before 1994. Therefore, the Board recommends that:
To reduce the number of post-impact fires in impact-survivable accidents involving existing production aircraft weighing less than 5700 kg, Transport Canada, the Federal Aviation Administration, and other foreign regulators conduct risk assessments to determine the feasibility of retrofitting aircraft with the following:
- selected technology to eliminate hot items as a potential ignition source;
- technology designed to inert the battery and electrical systems at impact to eliminate high-temperature electrical arcing as a potential ignition source;
- protective or sacrificial insulating materials in locations that are vulnerable to friction heating and sparking during accidents to eliminate friction sparking as a potential ignition source; and
- selected fuel system crashworthiness components that retain fuel. A06-10
Transport Canada Response to Recommendations A06-08, A06-09 and A06-10
With reference to recommendation A06-09, over the years many amendments to Airworthiness Manual (AWM) 523/FAR 23 regulations have been adopted to achieve this objective and may address certain elements of this recommendation. Many aircraft identified in the TSB report were certified to design standards from 1960 or earlier. These aircraft would not have been subject to the revised standards and therefore the benefits of these changes will not necessarily be evident in the data used by the TSB due to the date when many of the affected airplanes were certificated.
With reference to recommendation A06-10, Transport Canada is not aware of industry application for the approval of such technology for retrofit in production aircraft. It is believed this type of technology for use in aviation is still largely in the research and development stage and will require further developing and testing before it can be certified for use in a wide variety of aircraft. Departmental officials cannot conduct a viable risk assessment or mandate post certification until it is established that pertinent technologies are available, viable and required. Prior to undertaking any of this, a study would be required to clearly identify the benefit of such an undertaking. The technology would have to be identified, certified and hundreds of aircraft designs would require evaluation.
The vast majority of small aircraft registered in Canada are of foreign design and the expertise for implementing modifications to those aircraft rests primarily with the responsible Civil Aviation airworthiness authorities. These recommendations have a significant international impact that would require Transport Canada to involve other airworthiness agencies, such as the European Aviation Safety Agency and the United States Federal Aviation Administration.
Transport Canada supports the TSB objective of reducing fatalities and serious injuries due to post-impact fires in general aviation aircraft however, implementation of these recommendations would require an immense resource effort. Unfortunately, the Department is not in a position to commit the necessary resources at this time.
Should you require further information, please contact Aviation Safety Analysis at asi-rsa@tc.gc.ca