Recommendation

The Office of Accident Investigation convened a Safety
Recommendation Review Board to review the enclosed responses to
your safety recommendations. As a result, the Review Board
classified your recommendations as follows:



(*IR19990152) 99.400 - "Closed - Acceptable Action"



This is in response to Safety Recommendation[s] 99.400, which
pertain[s] to passenger oxygen systems and cabin altitude alert
systems on Raytheon Model 200 Series aircraft. Safety
Recommendation 99.400 requested a review of the appropriateness of
the current maintenance procedures for the testing of automatically
deployable passenger oxygen systems and cabin altitude alert
systems to ensure complete system operation.



In assessing Safety Recommendation 99.400, the B200 Maintenance
Manual procedures for functional testing of the oxygen auto-deploy
system and the cabin altitude alert system were reviewed. The
procedures were found to be acceptable with the exception of
functional testing of the two barometric pressure switches (one for
the oxygen system and one for the annunciator system) installed in
the airplane. There is currently no provision to functionally cheek
the operation of either switch to ensure that it would provide the
required signal at the specified cabin altitude of 12,500 feet. To
address this issue, Raytheon Aircraft Company has agreed to revise
the affected maintenance manuals to add a procedure to functionally
check both barometric pressure switches referred to above.



In conclusion, this office considers the actions identified in this
letter to be satisfactory in addressing the safety concern.
Raytheon Aircraft Company has committed to making the necessary
changes to the maintenance manuals of the affected airplanes to
verify that the barometric pressure switches will actuate at the
required altitude.



Therefore, the Wichita ACO recommends that Safety Recommendations
99.400 be closed.