FAA proposes AD for twin Cessna icing

June 9, 2011

AOPA has several concerns about the FAA’s proposed airworthiness directive (AD) for Cessna twin-engine aircraft.

The FAA published a notice June 3 proposing an AD on Cessna 310, 320, 340, 401, 402, 411,414, and 421 twins, requiring the installation of a placard prohibiting flight into known icing conditions. The AD would affect 6,883 aircraft of U.S. registry, and would require installing a placard that increases published speed on approach 17 mph (15 knots) in case of an inadvertent encounter with icing.

The FAA proposed the AD based on investigations of 51 icing-related accidents and incidents over the last 30 years. An unusual flight characteristic seen in the set of accidents and incidents the FAA studied was the development of high sink speeds that resulted in hard landings, suggesting the need for better airspeed awareness of pilots flying airplanes with accumulations of airframe ice.

The certification of the aircraft listed in the proposed AD did not include a requirement “to provide to the pilot the types of operations and meteorological conditions (e.g. icing conditions) to which the operation of the airplane is limited by the equipment installed.” Therefore, “the pilot may not realize that, even with de-ice boots or other similar equipment installed, the airplane is not certificated for flight into known icing conditions,” the FAA said.

AOPA has several concerns with the FAA’s proposal as written. First, there is the concern that an AD of this type may create new operational problems such as overruns on landing. Raising airspeed on final by 15 knots would substantially increase landing distance, increasing the likelihood of overrun accidents, perhaps simply substituting one danger for another.

Secondly, an AD requiring the instillation of two cockpit placards may not be the best method to address pilot misunderstandings about aircraft icing certification standards and the effects of residual ice on aircraft performance. The FAA’s Small Airplane Certification Process Study of July 2009 addressed similar concerns, identifying a number of disconnects between the FAA and aircraft operators “due to an inadequate level of information sharing between the FAA Aircraft Certification Service (AIR) and the FAA Flight Standards Service (AFS).” Aircraft icing certification standards have changed substantially over the years. The FAA should provide operators with certification information for their particular aircraft, based on the date of initial certification and optional equipment installed, and give clear direction on the limitations of that certification. This type of information would be of value to the entire aviation community, not just twin Cessna aircraft.

AOPA supports educational efforts to improve safety and reduce the number of icing accidents that occur annually. Most important, it should be stressed that there are limits on all ice protection packages. No ice protection package is designed to allow unlimited flight in icing conditions and may not remove all ice, making performance considerations for residual ice important to all pilots. Ice protection equipment, regardless of the certification level, is simply a means to assist in escaping icing conditions.

The Air Safety Institute offers two interactive courses Accident Case Study: Airframe Icing and WeatherWise: Precipitation and Icing that teach pilots how to recognize the hazards of icing.

AOPA members are encouraged to submit comments on the proposed AD by July 18.