Anti Icing System In Aircraft - On 13 December 2017, control of an ATR 42-300 was lost just after it became airborne at night from Fond-du-Lac and it was destroyed by the subsequent terrain impact. Ten occupants sustained serious injuries from which one later died and all others sustained minor injuries.
The investigation found that the accident was primarily attributable to pre-takeoff ice contamination of the airframe with an inappropriate pilot response then preventing an achievable recovery. It was found that significant airframe ice accretion had gone undetected during an inadequate pre-flight inspection and that there was a more widespread failure to recognize airframe icing risk.
Anti Icing System In Aircraft
Most light aircraft are poorly equipped to deal with icing conditions. Some may have partial equipment intended only for escaping unexpected icing conditions. Unless your aircraft is FAA certified for flight into icing conditions, you must avoid entering areas of known icing.
Deicing Equipment
On 4 January 2002, a Bombardier Challenger 604 became very quickly uncontrollable as the crew attempted to rotate for lift off at Birmingham and within a few seconds it had crashed inverted near the airport passenger terminal killing all on board.
A rigorous investigation found that an uncontrollable roll had occurred after an aerodynamic stall attributable to frost on the wings which had been noticed but apparently not considered indicative of a need for de-icing. The exclusively FAA promoted notion of polished frost may have played a part in the pilots decision making and was considered to be dangerously misleading.
Deicing equipment removes structural ice after it forms. The two most common GA systems are inflatable boots and weeping wings. Weeping wings can also be considered anti-icing equipment if the fluid dispensing system is activated before ice accumulates.
On 4 March 2016, the flight crew of an ATR72-500 decided to depart from Manchester without prior ground de/anti icing treatment judging it unnecessary despite the presence of frozen deposits on the airframe and from rotation onwards found that manual forward control column input beyond
Aircraft Ice Protection Systems Simulation And Testing
Trim capability was necessary to maintain controlled flight. The aircraft was subsequently diverted. The investigation found that the problem had been attributable to ice contamination on the upper surface of the horizontal tailplane. It was considered that the awareness of both pilots of the risk of airframe icing had been inadequate.
On January 17, 2004 a Cessna 208 Caravan operated by Georgian Express, took off from Pellee Island, Ontario, Canada, at a weight significantly greater than the maximum permitted and with ice visible on the airframe. Shortly after take off, the pilot lost control of the aircraft and it crashed into a frozen lake.
On 9 April 2008, a BAe Jetstream 41 departed Aberdeen in snow and freezing conditions after the captain had elected not to have the airframe de/anti iced having noted the delay this would incur. During the climb in IMC, pitch control became problematic and an emergency was declared.
Full control was subsequently regained in warmer air. The investigation concluded that it was highly likely that prior to take off, slush and/or ice had been present on the horizontal tail surfaces and that, as the aircraft entered colder air at altitude, this contamination had restricted the mechanical pitch control.
Aircraft Ice Protection Systems Engineering
Ice protection systems and components play a crucial role in safe aircraft operation under icing conditions. Icing can damage the aerodynamic shape, increase aircraft drag and reduce its controllability. This impacts flight performance and safety. Such systems are usually installed in wings, nacelle intakes, pitot tubes, stabilizers and propellers and helicopter rotor blades.
It should be noted that fan blade ice which may be accumulated after the pre-start visual inspection, including while the engines are running at low thrust prior to take off, is removed by following prescribed engine handling procedures.
Since ice protection systems are mission-critical systems, their design, development, verification and certification fit into the Siemens Xcelerator product design and engineering, model-based systems engineering (MBSE) and verification management digital threads, where Simcenter performance engineering skill tools provide required
engineering data to support aircraft programs and processes. Not only do Simcenter solutions enable the sizing and optimization of the detailed design, but they also provide the elements for the proof of compliance based on virtual and physical test data.
System Simulation For Aircraft Ice Protection
This effectively contributes to aircraft program execution excellence by enabling you to stay on time and budget. On 2 April 2012, the crew of an ATR72-200 which had just taken off from Tyumen lost control of their aircraft when it stalled after the flaps were retracted and did not recover before it crashed and caught fire killing or seriously injuring all occupants.
The investigation found that the captain knew that frozen deposits had accumulated on the airframe but appeared to have been unaware of the danger of not having the airframe de-iced. It was also found that the crew had not recognized the stall when it occurred and had overpowered the stick pusher and pitched up.
On 11 January 2017, control of a Cessna Citation 560 departing Oslo on a short positioning flight was lost control during flap retraction when a violent nose-down maneuver occurred. The First Officer took control when the Captain did not react and recovered with a 6 g pullout which left only 170 feet of ground clearance.
A MAYDAY - subsequently canceled when control was regained - was declared and the intended flight was then completed without further incident. The investigation concluded that tailplane stall after the aircraft was not de-iced prior to departure was the probable cause of the upset.
Faa Certificated Vs Non-Hazard Systems
On 26 December 2007, the crew of a Bombardier Challenger 604 which had received a 2-stage ground de/anti icing treatment lost roll control as the aircraft got airborne from a snow-covered runway at Almaty in freezing fog and light snow conditions and it
crashed inside the airport perimeter before continuing through the perimeter fence and catching fire. The investigation concluded that the loss of control was probably caused by contamination of the wing leading edge with frozen deposits during the take off roll as a result of the crew's decision not to select wing anti-ice contrary to applicable procedures.
Secondly, the prevailing weather conditions must be assessed. If further adherence of contaminant to the airframe surfaces is currently occurring or anticipated prior to the time at which it is expected that the aircraft will get airborne, then a suitable ground anti-icing fluid should be applied.
In both cases, the time after the start of fluid treatment from which protection is provided by the fluids applied depends upon the prevailing conditions. The fluids are designed to shear off the aircraft surfaces to which they have been applied no later than the point at which the aircraft becomes airborne.
Wing Anti-Ice System Testing
This means that the ground application of fluids has no effect upon the risks which arise from the accretion of frozen deposits on the aircraft at any time after take off. These safety-critical systems are part of the certification process and must be considered during the aircraft program development and testing.
An integrated simulation and testing approach enables you to evaluate the performance of ice protection components and systems under ideal and worst-case scenarios. On 7 November 2016, severe airframe vibrations occurred to an Avro RJ-100 which, following ground de-icing, was accelerating in the climb a few minutes after departing from Gothenburg.
The crew were able to stop the vibrations by reducing speed but they declared an emergency and returned to land where significant quantities of ice were found and considered to have been the cause of the vibrations.
The investigation concluded that the failure of the de icing operation in this case had multiple origins which were unlikely to be location specific and generic safety recommendations were therefore made. System simulation allows you to define the optimal system sizing earlier in the design cycle.
Anti-Icing Component Analysis With Cfd Simulation
It enables a smooth integration of the resulting aircraft ice protection system with other pneumatic consumers and their coupling with the engine bleed air system. Moreover, you can perform what-if analyzes like air leaking from a bleed pipe and the impact on the overall system.
What's the difference between systems that are FAA approved for flight in icing conditions, which allow a pilot to legally challenge routine icing conditions, and "non-hazard" systems that do not? Basically: certification standards and testing. Approved systems have demonstrated that they can protect your airplane during icing conditions specified in the airworthiness regulations, while non-hazardous systems do not have that burden of proof.
In the case of non-hazardous systems installed on airplanes certified before 1977, non-hazardous systems were not even required to prove that they could shed ice! On 28 November 2004, the crew of a Bombardier Challenger 601 lost control of their aircraft soon after getting airborne from Montrose and it crashed and caught fire killing three occupants and seriously injuring the other three.
The investigation found that the loss of control had been the result of a stall caused by frozen deposits on the upper wing surfaces after the crew had failed to ensure that the wings were clean or utilize the available ground de/anti ice service.
Additional Issues
It was concluded that the pilots' lack of experience of winter weather operations had contributed to their actions/inactions. As a critical aspect for the safe operation of an aircraft, wing anti-icing systems must pass a qualification test.
The standard prescribes several dynamic tests, including random, shock and sine excitation tests, to be carried out to study their effect on the parts composing the anti-icing system. Multiple-output, multiple-input (MIMO) technology can help you make sure each excitation point is simultaneously excited with the appropriate loading.
Using this state-of-the-art technique enables test engineers to increase efficiency in the entire vibration qualification process. Weeping Wing—When activated, the deicing system pumps fluid from a reservoir through a mesh screen embedded in the leading edges of the wings and tail.
The liquid flows all over the wing and tail surfaces, deicing as it flows. It can also be applied to the propeller and windshield. First of all, the aircraft must be inspected for signs of contaminant already adhering to surfaces and where found on surfaces which must be free of contaminant, it must be removed using a suitable ground de-icing fluid.
Note: Although the Association of European Airlines (AEA) ceased to exist in 2016, the most recent of their publications still contain some pertinent information. Readers are cautioned to validate the recommendations of these guidebooks using more current information sources.
On 4 March 2013, a Beechcraft Premier 1A stalled and crashed soon after take off from Annemasse. The investigation concluded that the loss of control was attributable to taking off with frozen deposits on the wings which the professional pilot flying the privately-operated aircraft had either not been aware of or had considered insignificant.
It was found that the aircraft had been parked outside overnight and that overnight conditions, particularly the presence of a substantial quantity of cold-soaked fuel, had been conducive to the formation of frost and that no airframe de/anti icing facilities had been available at
Annemasse. On 04 November 2003, the crew of a de Havilland DHC-8-100 which had been de/anti iced detected a pitch control restriction as rotation was attempted during take off from Ottawa and successfully rejected the take off from above V1.
The investigation concluded that the restriction was likely to have been the result of a remnant of clear ice migrating into the gap between one of the elevators and its shroud when the elevator was moved trailing edge up during control checks and observed that detection of such clear ice
Remnants on a critical surface wet with de-icing fluid was difficult. Propeller Anti-Ice—Ice often forms on the propeller before it is visible on the wing. Props are treated with deicing fluid applied by slinger rings on the prop hub or with electrically heated elements on the leading edges.
After the system type is chosen and the component sizing is completed using system simulation, the components require a more detailed 3D CFD simulation for their individual performance and optimization. The component performance can then be fed back into or coupled with a system simulation model with more accurate parameters to increase system simulation accuracy.
On 31 January 2005, the pilot of a Cessna 208 which had just taken off from Helsinki lost control of their aircraft as the flaps were retracted and the aircraft stalled, rolled to the right and crashed within the airport perimeter.
The investigation found that the take off had been made without prior airframe de/anti icing and that accumulated ice and snow on the upper wing surfaces had led to airflow separation and the stall, a condition which the pilot had failed to recognize or respond appropriately to.
for undetermined reasons. On 27 December 1991, an MD-81 took off after airframe ground de/anti icing treatment but soon afterwards both engines began surging and both then failed. A successful crash landing with no fatalities was achieved four minutes after take off after the aircraft emerged from the cloud approximately 900 feet above the terrain.
There was no post-crash fire. The investigation found that undetected clear ice on the upper wing surfaces had been ingested into both engines during rotation and initiated engine surging. Without awareness of the aircraft's automated thrust increase system, the pilot response did not control the surging and both engines failed.
Developing anti-icing and de-icing systems from component level to systems integration should be considered early in the design stage to stay on budget and schedule. Simulation and testing play a major role in the development and certification process to ensure the flight safety under icing conditions.
Failure to remove contamination from an airframe and/or to protect it from acquiring further contamination before it becomes airborne may result in sudden loss of control at or shortly after take off. In the case of aircraft with rear mounted engines, any ice on the inner wings of an aircraft at take off may be shed and ingested into the engines causing a partial or total loss of thrust.
On 4 March 2019, a Boeing 767-300 crew lost directional control of their aircraft as speed reduced following their touchdown at Halifax and were unable to prevent it from being rotated 180° on the icy surface before coming to a stop facing the runway landing threshold.
The investigation found that the management of the runway safety risk by the airport authority had been systemically inadequate and that the communication of what was known by ATC about the runway surface condition had been incomplete.
A number of subsequent corrective actions taken by the airport authority were noted. In respect of engines, frozen deposits within the intakes including on the fan blades of jet engines may detach and be ingested by the same engine(s) during the subsequent application of take off power, with the attendant risk of adverse effects on engine performance during
the potentially critical stage of initial climb, including the possibility of engine flameout. Inflatable Boots—When activated, the inflatable rubber strips—attached to and conforming to the leading edge of the wing and tail surfaces—are pressurized with air and expand, breaking ice off the boot surfaces.
Suction deflates the boots and they return to their original shape. Use of thickened Type 2 and Type 4 ground de/anti icing fluids has sometimes resulted in fluid residues accumulating in aerodynamically quiet areas of the external airframe structure, particularly in the gap between the leading edge of the elevator and the horizontal stabilizer and also in the
gap between the leading edge of the ailerons and the wing structure. When this residue is subsequently re-hydrated and then exposed to sub zero temperatures in flight, it freezes and can then result in primary flight control restrictions on aircraft types such as the BAE 146/Avro RJ series and the DC9/MD 80/90 series.
which have at least some unpowered flight controls. After a number of serious incident reports, many operators of affected aircraft types have adapted their aircraft maintenance procedures to carry out appropriate inspections and residue removal when these fluids have been applied.
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