Airworthiness Directive · Amendment 39-11980 · Lockheed Model 188A and 188C Series Airplanes
Lockheed Model 188A and 188C Series Airplanes
All Model 188A and 188C series airplanes, certificated in any category.
This amendment adopts a new airworthiness directive (AD), applicable to all Lockheed Model 188A and 188C series airplanes, that requires a revision of the Airplane Flight Manual (AFM) to add procedures for donning the flightcrew oxygen masks when the cabin altitude warning horn is activated. The actions specified by this AD are intended to prevent incapacitation of the flightcrew as a result of lack of oxygen and consequent loss of control of the airplane due to absence of AFM procedures for donning the flightcrew oxygen masks when the cabin altitude warning horn is activated.
To prevent incapacitation of the flightcrew and consequent loss of control of the airplane due to delays in donning oxygen masks in response to the activation of the cabin altitude warning horn; accomplish the following:
(a) Within 90 days after the effective date of this AD, revise the Emergency Procedures Section of the FAA-Approved Airplane Flight Manual (AFM) to include the following (which may be accomplished by inserting a copy of this AD in the AFM):
“Low Cabin Pressure Warning Light Comes On and Horn Starts Blowing
a. Oxygen Masks—Don. Select 100% oxygen.
b. If conditions dictate, initiate emergency descent.
c. Check cabin differential pressure gage.
1. If differential pressure is below 13.34 + 0.30 in. Hg, lower cabin altitude selector wheel.
2. If differential pressure is at 13.34 + 0.30 in. Hg, descend to lower aircraft altitude.
Note: Warning horn can be silenced with cabin altitude warning horn switch.”
