AD NUMBER: 2008-04-17
SUBJECT: Airworthiness Directive 2008-04-17 SUMMARY: We are adopting a
new airworthiness directive (AD) for the products listed above.
This AD results from mandatory continuing airworthiness
information (MCAI) originated by an aviation authority of another
country to identify and correct an unsafe condition on an aviation
The MCAI describes the unsafe condition as: Several cases have
been reported where the pilot, co-pilot or observer utility light
system has failed, resulting in a burning smell within the
An investigation has revealed that, due to the orientation and
location of the carbon molded potentiometers used to control the
intensity of the light, the potentiometers can fail and overheat in
such a way that burning of the ceiling panel and the associated
insulation blanket could occur. This could lead to the presence of
smoke in the cockpit, requiring that the pilots carry out the
appropriate emergency procedure.
We are issuing this AD to require actions to correct the unsafe
condition on these products.