737 RTO procedure and auto speed brake deployment question

[CHfour]

@skyjob

Here it is:
BOEING COMMERCIAL AIRPLANES
FLIGHT OPERATIONS TECHNICAL BULLETIN
NUMBER: 737-12-1
DATE: January 31, 2012
This bulletin provides information which may prove useful in airline operations or airline training. The information
provided in this bulletin is not critical to flight safety. The information may not apply to all customers; specific
effectivity can be determined by contacting The Boeing Company. This information will remain in effect
depending on production changes, customer-originated modifications, and Service Bulletin incorporation.
Information in this bulletin is supplied by The Boeing Company and may not be approved or endorsed by the FAA
at the time of writing. Appropriate formal documentation will be revised, as necessary, to reflect the information
contained in this bulletin. For further information, contact Boeing Commercial Airplanes, Chief Pilot – Flight
Technical and Safety, P. O. Box 3707, Mail Code 20-95, Seattle, Washington 98124-2207; Phone [phone]-
8024; or Facsimile [phone].
SUBJECT: Rejected Takeoff (RTO) Maneuver
ATA NO: 0200-00
APPLIES TO: All 737 Airplanes
REASON: To provide background information about the 737 RTO maneuver and to
emphasize the requirement to follow the three-step maneuver.
BACKGROUND INFORMATION
In the 737NG Airplane Flight Manual (AFM), the Rejected Takeoff (RTO) non-normal
maneuver requires the Captain to:
 Simultaneously close the thrust levers (disengage the autothrottles, if required) and apply
maximum manual wheel brakes or verify operation of RTO autobrakes.
 If RTO autobrakes is selected, monitor system performance and apply manual wheel
brakes if the AUTO BRAKE DISARM light illuminates or deceleration is not adequate.
 Raise SPEED BRAKE lever.
 Apply maximum reverse thrust consistent with conditions.
 Continue maximum braking until certain the airplane will stop on the runway.
This is commonly known as a three-step maneuver, i.e., thrust levers, speed brakes and reverse
thrust.
Page 2 of 2
During certification tests for a CFM56-7 engine EEC software upgrade, a remote condition was
identified in which rapid thrust reverser deployment after operating at high forward thrust could
exceed thrust reverser design load limits. This condition was determined not to be unique to this
EEC software upgrade, as the same condition existed in all previous EEC software versions. The
condition is, therefore, possible on all 737NG airplanes.
The 737NG reverser blocker door design is such that the design load of the thrust reverser inner
wall is highest when the translating sleeve is 60% deployed. To prevent exceeding the design
load, the engine must be spooled down before reverse thrust is selected. Tests determined that a
minimum of 3.1 seconds between high forward thrust and thrust reverser deployment was
needed to ensure the thrust reverser design load limits are not exceeded. Flight tests have shown
that this 3.1 second delay can be achieved by sequentially retarding the thrust levers to idle,
manually raising the SPEED BRAKE lever, and then deploying the thrust reversers. Flight tests
have also shown that a two-step maneuver, i.e., retarding the thrust levers to idle and deploying
the thrust reversers, thus automatically raising the speed brakes, does not provide the needed
time delay.
After discussions with the FAA, it was decided that all 737NG airplanes must use the three step
RTO maneuver as described above and in AFM Section 2, Page 14.
For procedural commonality between the 737NG, 737-300/400/500 and 737-100/200, Boeing
will not approve a different procedure for the earlier 737 models.
OPERATING INFORMATION
For the 737NG, the two-step RTO maneuver, i.e., retarding the thrust levers to idle and
deploying the thrust reversers, thus automatically raising the speed brakes, is a violation of
engine certification requirements. These requirements are reflected in the RTO maneuver in the
737NG AFM.
To ensure compliance with engine certification requirements, the RTO maneuver should be
accomplished as a three-step maneuver: close the thrust levers, manually raise the SPEED
BRAKE lever, and apply reverse thrust up to the maximum amount consistent with conditions.
For procedural commonality, the same three-step RTO maneuver is applicable to 737-100/200
and 737-300/400/500 airplanes.