Originally Posted by
PAPI-74
With high lift slats / LE flaps the boundary layer is extremely energized and separation leading to wing stall is unlikely on that aircraft, with frost on the cells anyway. Other aircraft, however, are not so fortunate and with rear mounted engines and a T tail - a definite no-no.
The fuel is heated from access heat from a heat exchanger from either excess bleed air or from the engine oil. This thaws any ice crystals that would clog the filters, bringing the fuel to approx room temp, which may be enough to thaw the hoar frost on the cells on the 767 / 757.
This was ground icing on top of the wing. In flight icing is typically more on the leading edge, so it is different. But here is an interesting statement about the 767 with regards to in flight icing to show its capability.....
"According to the manufacturer, the aircraft was designed so that flight in icing conditions should not affect its control, trim, or handling. The horizontal tail, with no de-icing capability, was designed to minimize its susceptibility to the accumulation of ice. The size of the horizontal tail was designed to allow it to operate at tail lift levels at or below the levels where leading edge ice would affect the tail's ability to generate the required lift.
The CAI Boeing 767 Operations Procedure, which discusses the effect of wing ice contamination, indicates that lift decreases and drag increases at high angles of attack. The manufacturer indicates that there is no lift loss attributable to ice contamination until the wing angle of attack increases above 15°."
Aviation Investigation Report A96A0035 - Transportation Safety Board of Canada