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Interim Recommendation issued to: Federal Aviation Administration (FAA)

Recommendation details
Output No: IR19990155
Date issued: 07 October 1999
Safety action status:
Background: Why this Interim Recommendation was developed

Output text

The Bureau of Air Safety Investigation recommends that the Federal Aviation Administration consider the incorporation of an audible warning to operate in conjunction with the cabin altitude alert system on Beech aircraft, and other aircraft so equipped.

As a result of the investigation into this safety deficiency, the Bureau simultaneously issues the following interim recommendations:

IR19990150

The Bureau of Air Safety Investigation recommends that Raytheon Aircraft develop and publish methods for the in-situ testing of the automatically deployable passenger oxygen activation system and the cabin altitude alert system on Beechcraft aircraft, to ensure complete system operation.

IR19990151

The Bureau of Air Safety Investigation recommends that the Civil Aviation Safety Authority reassess 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.

IR19990152

The Bureau of Air Safety Investigation recommends that the Federal Aviation Administration reassess 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.

IR19990153

The Bureau of Air Safety Investigation recommends that Raytheon Aircraft consider the incorporation of an audible warning to operate in conjunction with the cabin altitude alert system on all Beech aircraft so equipped.

IR19990154

The Bureau of Air Safety Investigation recommends that the Civil Aviation Safety Authority consider the incorporation of an audible warning to operate in conjunction with the cabin altitude alert system on Beech aircraft, and other aircraft so equipped.

Initial response
Date issued: 31 March 2000
Response from: Federal Aviation Administration (FAA)
Action status: Closed - Not Accepted
Response text:

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:

(*IR19990155) 99.401 - "Closed - Acceptable Alternate Action"

This is in response to Safety Recommendation[s] 99.401, which pertain[s] to passenger oxygen systems and cabin altitude alert systems on Raytheon Model 200 Series aircraft. Safety Recommendation 99.401 requested incorporation of an audible warning to operate in conjunction with the cabin altitude alert system on these aircraft and other aircraft similarly equipped.

Safety Recommendation 99.401, which requests consideration of an audible warning to operate in conjunction with the existing visual warning system, has also been reviewed. The existing system utilizes a red "ALT WARNING" annunciator light. Although no aural tone is present when the red light illuminates, both master warning flashers begin flashing to bring the pilot's attention to the appropriate annunciator. In reviewing this recommendation, the certification basis for the Raytheon Model 200 Series airplanes was reviewed. At the amendment level established in the certification basis, Section 23.841 (f) states: "...an aural or visual signal (in addition to cabin altitude indicating means) meets the warning requirement for absolute cabin pressure limits". Furthermore, the corresponding Part 25 (Transport Category) requirement (Section 25.841(b)(6)) states: "...an aural or visual signal (in addition to cabin altitude indicating means) meets the warning requirements for cabin pressure altitude limits ... ). Based on the above, the FAA has clearly never specifically required an aural cabin altitude warning. Although it is recognized that adding an aural warning is a desirable enhancement of the system, requiring such a warning for the existing fleet is not considered necessary to meet the minimum airworthiness standards.

In conclusion, this office considers the actions identified in this letter to be satisfactory in addressing the safety concern. The existing visual warning system for high cabin altitude is deemed acceptable.

Therefore, the Wichita ACO recommends that Safety Recommendation[s] 95.401 be closed.

 
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Last update 01 April 2011