The US Federal Aviation Admini­stration is proposing new certification standards for detecting and coun­tering airframe ice on new transport category aircraft.

The notice of proposed rulemaking comes after a review of icing accidents and incidents by an FAA-sanctioned aviation rulemaking advisory committee.

The effort is to "im­prove the level of safety for new airplane designs for operations in icing conditions", says the FAA, adding that the proposal also "partially" addresses two NTSB recommendations related to airframe icing. One stemmed from the 1994 crash of an American Eagle ATR 72 in Indiana that killed 68, the other was tied to the 1997 crash of a Comair Embraer EMB-120 Brasilia in Michigan, where 29 people died.

Under the proposal, aircraft manufacturers will have to provide one of three tools for detecting and countering ice: a redundant "primary" ice-detection system that automatically activates the aircraft's airframe icing protection system (IPS) or alerts the crew to do so an "advisory" ice detection system (a non-redundant sensor), backed up by definitions of the visual cues of icing, both of which alert the flightcrew to activate the airframe IPS or the cues needed to identify the conditions conducive to airframe icing based on temperature and visible moisture so that the crew can activate the IPS.

The FAA says the IPS should "automatically cycle". Failing that, the system must alert the crew when to manually cycle the IPS.

The third option will be the lowest cost to implement as it will require only a change to the aircraft flight manual. More costly are the ice-detection systems, which the FAA says will cost about $500,000 to certificate for a particular aircraft model and as much as $15,000 in equipment for each aircraft.

Source: Flight International