AD NUMBER: 2007-10-07
SUBJECT: Airworthiness Directive 2007-10-07
SUMMARY: We are superseding an existing airworthiness
directive (AD) by adopting a new AD for the products listed above.
This AD results from mandatory continuing airworthiness information
(MCAI) issued by an aviation authority of another country to
identify and correct an unsafe condition on an aviation product.
The MCAI describes the unsafe condition as: The deterioration of
the splines on the HP/LP pump assembly drive shaft may eventually
interrupt fuel supply andcause uncommanded in-flight engine
shutdown. The result may be an emergency autorotation landing or,
at worst, an accident. Two cases of in-flight shutdown resulting
from splines deterioration have been reported for the ARRIUS 2B1
engine, which has the same HP/LP pump drive design as the ARRIEL 2.
These cases prompted us to require the inspection at 500 hours and
each time the HMU is removed/installed. This AD modifies the
content of the previous DGACFrance AD F-2005-188 (EASA Approval
Number 2005-6408) in adding a one time inspection within 30
operating hours from effective date of this AD as well as HMU
re-installation according to a maintenance task modified to avoid
this kind of wrong assembly. This has been set up following one
case of improper clipping of the coupling shaft onto the drive gear
shaft, which resulted in an uncommanded in-flight engine shutdown
(on a twin engine rotorcraft). This precaution measure has been
taken only on engines powering single engine rotorcraft. This AD
requires actions that are intended to address the unsafe condition
described in the MCAI.