European regulators are mandating the fitting of on-ground wing leading-edge heating systems (OGWLEHS) on Fokker 70 and Fokker 100 aircraft following a series of icing-related accidents.
The action comes shortly after the publication of the final report into the loss of a Fokker 100 by Air France-affiliate Regional at Pau on 25 January 2007, which was the latest in which undetected wing-icing was implicated.
The European Aviation Safety Agency (EASA) says in an airworthiness directive that the OGWLEHS was fitted to the final few aircraft off the production line following the loss of a Palair Macedonia Fokker 100 on 5 March 1993 at Skopje in which 83 people died.
It notes: "During the last few years at least two serious winter operation events with [the aircraft] are known to have occurred, associated with leading-edge ice contamination, as a result of which the two aircraft were written off.
"Apparently the required inspections for wing contamination by ice, frost or snow and the associated de-/anti-icing treatments are not always fully complied with in the actual operational environment. As a consequence a clean aircraft prior to take-off cannot be taken for granted."
The agency does not specify to which incidents it is referring, but one is probably the Pau crash and the other may be the loss of an Austrian Airlines Fokker 70 at Munich on 19 January 2004 as a result of suspected engine and possibly wing leading-edge icing.
It adds: "If these events would have been directly attributable to design-related causes this occurrence rate would be beyond the acceptable limit for continuing airworthiness. However, these events are established to have been caused by operational (human) factors instead.
"Nevertheless the potential of further accidents due to similar causes can be more effectively reduced by a single design change rather than by additional operational measures (however necessary) to improve the operational assurance of a clean aircraft take-off."
The work has to be completed within two years. KLM Cityhopper remains by far the biggest operator of the family, but other significant operators in Europe are Austrian Airlines, Brit Air, and Regional. Elsewhere key operators include Click Mexicana, Iran Air, Iran Aseman Airlines, OceanAir of Brazil, and SAM Colombia.