maintenance firm Fokker Services has issued a set of precautionary
recommendations for airframe and engine anti-icing procedures on Fokker 70 and
100 aircraft following the forced landing by an Austrian Airlines aircraft outside
Munich this month.
Services says that, although the precise circumstances of the 5 January
accident have yet to be determined, the possibility that engine or wing icing
contributed to the crash has prompted the company to reassess anti-icing
recommendations on the type.
have so far determined that, although the pilots activated anti-ice systems on
the aircraft, ice-impact protection panels inside the Rolls-Royce Tay engines
broke away shortly before the twin-jet was due to touch down at Munich.
involved [investigating] parties have strong reasons to believe that the
Austrian Airlines aircraft was operating in exceptional icing conditions,” says
meant that, as far as can be seen at present, a substantial mass of ice was
able to accumulate in a short time on the engine air intakes and possibly also
on the wing leading edges.”
the pilots switched on the anti-icing systems, it says, the accumulated ice
could have broken away and caused the ice-impact panels to detach: “These are
believed to have subsequently blocked the air flow in the engines, as a result
of which the engines were unable to develop sufficient thrust and an emergency
landing became necessary.”
the new advisory, engine anti-icing must be switched on during all ground or
flight operations where the total air temperature is below 6°C, irrespective of
the presence of visible moisture.
anti-icing systems must be switched on during flight operations when any of
three possible conditions arise: ice build-up is observed, the aircraft’s icing
alert is activated, or icing conditions are anticipated. Icing conditions occur
when the total air temperature is below 6°C and visible moisture is present.
precautionary measures are recommended until further notice, pending further
results from the investigation,” says Fokker Services. The advisory applies to
Rolls-Royce Tay 620- and Tay 650-powered aircraft.
Airlines commenced an immediate inspection of its Fokker 70 fleet in the wake
of the accident and has been replacing a number of ice-impact panels in the
engines of its aircraft.