Airworthiness Directive · Amendment 39-15728 · Boeing Model 737 Airplanes
Boeing Model 737 Airplanes
This AD applies to all Boeing Model 737-100, -200, -200C, -300, -400, -500, -600, -700, -700C, -800, -900, and -900ER series airplanes, certificated in any category.
We are adopting a new airworthiness directive (AD) for all Boeing Model 737 airplanes. This AD requires revising the airplane flight manual to include a new flightcrew briefing that must be done before the first flight of the day and following any change in flightcrew members, and to advise the flightcrew of this additional briefing. This AD results from continuing reports that flightcrews have failed to recognize and react properly to the cabin altitude warning horn. We are issuing this AD to prevent failure of the flightcrew to recognize and react properly to a valid cabin altitude warning horn, which could result in incapacitation of the flightcrew due to hypoxia (lack of oxygen in body) and consequent loss of airplane control.
Comply with this AD within the compliance times specified, unless already done.
Within 120 days after the effective date of this AD, revise the Limitations Section of the applicable Boeing 737 AFM to include the following statement. This may be done by inserting a copy of this AD into the applicable AFM.
“CABIN ALTITUDE WARNING TAKEOFF BRIEFING (required by AD 2008-23-07)
With the CABIN ALTITUDE and TAKEOFF CONFIG lights not installed, or installed but not activated:
As part of the Takeoff Briefing before engine start for the first flight of the day or following any change of either flightcrew member, the pilot-in-command will ensure the Cabin Altitude Warning indications and procedures are briefed in accordance with the procedures contained in the Normal Procedures section of this manual.”
(g) Within 120 days after the effective date of this AD, revise the Normal Procedures Section of the applicable Boeing 737 AFM to include the following statement. This may be done by inserting a copy of this AD into the applicable AFM.
“CABIN ALTITUDE WARNING TAKEOFF BRIEFING (required by AD 2008-23-07)
The following briefing is important to further reduce the risk of flightcrew incapacitation due to hypoxia. Because of the dual purpose of the intermittent cabin altitude/takeoff configuration warning horn, this briefing serves to remind flightcrews that the sounding of the cabin altitude warning horn in flight requires immediate action, beginning with the immediate donning of oxygen masks. Upon completion of the applicable WARNING HORN—CABIN ALTITUDE OR CONFIGURATION non-normal checklist memory items, other alerts and indications on the flight deck (e.g., air/ground sensing system failures, equipment cooling OFF, etc.) may then be addressed.
Memory item cabin altitude warning indications and procedures must be briefed on airplanes in which the CABIN ALTITUDE and TAKEOFF CONFIG lights are not installed, or are installed but not activated. This will be included as an additional item on the Takeoff briefing before engine start for the first flight of the day, or following any change of either flightcrew member.
The briefing must include the following items.
—Whenever the intermittent warning horn sounds in flight:
1. Immediately, don oxygen masks and set regulators to 100%.
2. Establish crew communications.
3. Do the CABIN ALTITUDE WARNING OR RAPID DEPRESSURIZATION checklist.
—Both pilots must verify on the overhead Cabin Altitude Panel that the cabin altitude is stabilized at or below 10,000 feet before removing oxygen masks.”
