MN-FLT-OH-201
B-6 Page 1 of 2
Covers
File Highlight
Nuisance Illumination of the Wing Anti-Ice VALVE Lights
GOT-6
Flight Crew Operations Manual Bulletin
for
Gol Linhas Aereas S.A.
Number:
GOT
-
6
IssueDate:
April 4, 2018
Subject:
Nuisance Illumination of the Wing Anti-Ice VALVE Lights
Reason:
This bulletin informs flight crews how to prevent nuisance illumination
of the wing anti-ice VALVE lights when using wing anti-ice with idle
thrust settings.
THE FOLLOWING PROCEDURE AND/OR INFORMATION IS EFFECTIVE UPON RECEIPT
Background Information
During 737-8 flight tests, illumination of the amber wing VALVE lights occurred
during use of the wing anti-ice system under the following conditions:
• Engine idle thrust descent above FL230
• Selecting wing anti-ice ON with engine anti-ice already in use.
Under the above conditions the L VALVE or R VALVE light can illuminate for
approximately 15 seconds even with sufficient air pressure to operate the wing
anti-ice valve. Illumination of the L VALVE or R VALVE light for more than
approximately 10 seconds illuminates the two master caution lights and the
amber ANTI-ICE light on the system annunciator panel.
The cause for the illumination of the L VALVE or R VALVE light is that the
pressure switch sensing a transient bleed air pressure drop downstream of the
wing anti-ice valve. It is important to note that even though the L VALVE or R
VALVE can illuminate for approximately 15 seconds, sufficient bleed air
pressure is available to provide wing anti-ice protection.
This anomaly affects 737-7/-8/-9 airplanes prior to Line Number 7000. For these
airplanes Boeing will communicate appropriate modification instructions as soon
as they become available.
Information in this 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.
March 1, 2021