Document ID: chunk:federal_register_of_legislation:F2009L00514:body:0:p2
Version: federal_register_of_legislation:F2009L00514
Segment Type: other
Provision Reference: 
Character Range: 2790–5097

excluded over the full calendar year and the operator's complete operating network, the operator may consider submitting an application to obtain an exemption for the actions required by this Directive.
                Note 4:  EASA AD 2009-0008 refers.
Compliance:     Within 24 calendar months after the effective date of this Directive.

             This Airworthiness Directive becomes effective on 12 March 2009.
Background:  Subsequent to a fatal accident with a Fokker F28 Mark 0100 in 1993, the last few aircraft from the production line were fitted with an OGWLEHS, which activates the wing antiicing system on the ground when engine anti-icing is selected ON.  The standard wing anti-icing system, if selected ON, operates only during flight.

             This modification, which provides an additional safety feature during winter operation, was also made available as an option to in-service aircraft through Pro-Forma Service Bulletin SBF100-30-018 in 1997.

             During the last few years, at least two serious winter operation events with F28 Mark 0100 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.

             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.

             It is highly probable that the two aircraft losses referred to above would not have occurred if the aircraft had been equipped with an OGWLEHS.

James Coyne
Delegate of the Civil Aviation Safety Authority

27 January 2009