Information in this Flight Crew Operations Manual (FCOM) bulletin is recommended by The Boeing Company, but may not be FAA approved at the time of writing. In the event of conflict with the FAA approved Airplane Flight Manual (AFM), the AFM shall supersede. The Boeing Company regards the information or procedures described herein as having a direct or indirect bearing on the safe operation of this model airplane.
THE FOLLOWING PROCEDURE AND/OR INFORMATION IS EFFECTIVE UPON RECEIPT
Background Information
An operator recently reported an anomaly while attempting a PA announcement using the audio panel PTT switch with the Control Wheel Microphone/Interphone switch latched in the INT (flight interphone) position. If the Control Wheel Microphone/Interphone switch is latched in the INT position and the associated audio panel PTT Switch or hand microphone is used with the PA Transmitter Select switch selected, transmissions cannot be made on the PA system. The aft aisle PA handset or PA hand microphone continue to function normally in this condition. The other pilot’s PTT switch and hand microphone operate normally if the associated Control Wheel Microphone/Interphone switch is not also latched in the INT position.
Administrative Information
Insert this bulletin behind the FCOM Bulletin Record Page in Volume 1 of your FCOM. Amend the FCOM Bulletin Record Page to show Bulletin ELF-22 "IN EFFECT" (IE)
This condition is under investigation. This FCOM bulletin remains in effect until further notice.
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Flight Crew Operations Manual Bulletin No. ELF-22,dated March 12, 1999 (continued)
Please send all correspondence regarding FCOM bulletin status to one of the following addresses:
Mailing Address: Manager 737, Flight Technical Integration & Data
Boeing Commercial Airplane Group
P. O. Box 3707 MS 20-89
Seattle, WA 98124-2207
USA
Fax Number: (206) 662-7812
Telex: 329430 Station 627
SITA: LKEBO7X
E-MAIL: FTID@Boeing.com
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Flight Crew Operations Manual Bulletin
for
The Boeing Company Seattle, Washington 98124-2207
737
Number: ELF-25
Date: December 03, 1999 Document Effectivity: Subject: Maneuvering Speeds for 737-100/200/300/400/500 Reason: Revise the Boeing Recommended Maneuvering Speeds
Information in this Flight Crew Operations Manual (FCOM) bulletin is recommended by The Boeing Company, but may not be FAA approved at the time of writing. In the event of conflict with the FAA approved Airplane Flight Manual (AFM), the AFM shall supersede. The Boeing Company regards the information or procedures described herein as having a direct or indirect bearing on the safe operation of this model airplane.
THE FOLLOWING PROCEDURE AND/OR INFORMATION IS EFFECTIVE UPON RECEIPT
Background Information
In March 1999, the FAA released a Flight Standards Information Bulletin for Air Transportation (FSAT) number 99-2, titled “Maneuvering Speeds and Recovery Procedures for Boeing 737 Airplanes.” The FSAT recommended that “For the interim period and prior to completion of fleet retrofit” (of a redesigned rudder power control unit (PCU) and the installation of both a digital yaw damper system and a rudder pressure reducer (RPR)), “that all Block Speeds for flap settings of UP, 1, 5, and 10...be increased by at least 10 knots and that these increased speeds be used in lieu of the published Block Speeds.”
Boeing issued an Operations Manual Bulletin (OMB). dated May 28, 1999 that provided revised Block Speeds to be used in compliance with the FSAT pending installation of the RPR. Boeing also advised that analysis of crossover speeds with the RPR installed was in work, and upon completion of analysis updated Block Speeds would be provided. Boeing has completed this analysis. The purpose of this bulletin is to provide updated Block (maneuvering) Speeds for 737 airplanes with the RPR installed. This bulletin does not apply to the 737-600/700/800.
The maneuvering speeds recommended by Boeing are referred to as Block Speeds. Block Speeds are provided for a specific flap setting and a range of weights. The lateral-directional static balance speed has been referred to as “crossover” speed. This is the airspeed that requires full lateral (roll) control from
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Flight Crew Operations Manual Bulletin No. ELF-25,dated December 03, 1999 (continued)
the ailerons and spoilers to counteract roll due to yaw caused by a full rudder input. At speeds slower than the crossover speed, with full rudder input, the roll induced by the rudder starts to exceed the lateral control authority.
The Rudder Pressure Reducer (RPR) lowers hydraulic pressure to the rudder PCU during non-critical phases of flight, thereby limiting the amount of rudder deflection. Reduced rudder deflection lowers the speed at which crossover may occur. The crossover speed is not a fixed speed but varies as a function of g load and CG. Reducing g load lowers the crossover speed. As described in the Uncommanded Yaw and Roll non-normal checklist, if uncommanded yaw or roll is experienced, maintain control of the airplane with all available flight controls. If roll is uncontrollable, immediately reduce pitch attitude (angle of attack) and increase speed. Unloading the airplane by decreasing back pressure on the control column improves roll control effectiveness.
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