Airworthiness Directive · Amendment 39-15688 · Hawker Beechcraft Corporation Model 390 Airplanes
Hawker Beechcraft Corporation Model 390 Airplanes
This AD applies to Model 390 airplanes, serial numbers RB-1 and RB-4 through RB-238, that are certificated in any category.
The FAA is adopting a new airworthiness directive (AD) for certain Hawker Beechcraft Corporation Model 390 airplanes. This AD requires you to modify the cabin barometric pressure switch and cabin altitude high switch installations and perform a functional test of the switches and related systems. This AD results from the possibility of barometric pressure switch electrical connections being incorrectly connected or inadvertently disconnected. We are issuing this AD to modify the cabin barometric pressure switch and cabin altitude high switch to prevent them from becoming incorrectly connected or inadvertently disconnected, which may result in no CABIN ALT HI annunciation in the cockpit and no automatic deployment of the cabin oxygen masks. This failure could lead to incapacitation of the crew due to hypoxia with possible inability to control the airplane.
To address this problem, you must do the following, unless already done:
| Action | Compliance | Procedures |
|---|---|---|
| (1) Modify the cabin barometric pressure switch and cabin altitude high switch installations. | Within 25 hours time-in-service (TIS) after October 20, 2008 (the effective date of this AD) or within 30 days after October 20, 2008 (the effective date of this AD), whichever occurs first. | Follow Hawker Beechcraft Mandatory Service Bulletin SB 21-3899, original issue, dated May 2008. |
| (2) Perform a functional test of the switches and related systems: (i) If, before the effective date of this AD, you did the flight test method in Part II of the Accomplishment Instructions of the service bulletin referenced in the Procedures column of this paragraph, then the action of paragraph (e)(2) of this AD is not required provided it was done after the modification required in paragraph (e)(1) of this AD. (ii) After the effective date of this AD, the flight test method described in paragraph (e)(2)(i) of this AD is prohibited. | Before further flight after the modification of the cabin barometric pressure switch and cabin altitude high switch installations specified in paragraph (e)(1) of this AD. | Following Part I—Ground Test Method paragraph 3, Accomplishment Instructions of Hawker Beechcraft Mandatory Service Bulletin SB 21-3899 original issue, dated May 2008. |
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
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