To inform flight crews of missing EICAS OPS Version 6 advisory-level message logic and to provide temporary operating instructions with OPS Version 6 installed.
Boeing and Rockwell Collins have confirmed the EICAS advisory-level L ENG FUEL FILT alert message is not available on airplanes installed with EICAS computer P/N S242N701-1001 with Operating Program Software (OPS) Version 6. This software version is installed by incorporation of Boeing Service Bulletin 767-31-0236, or production equivalent.
Each engine fuel system is equipped with a filter to remove contaminants and a pressure relief valve to allow bypass of an obstructed filter element. A pressure differential switch provides EICAS alerting of filter element obstruction prior to pressure relief valve actuation and filter bypass. Contaminants in the fuel system may result in erratic engine operation and flameout.
The EICAS advisory-level L ENG FUEL FILT alert message indicates an impending fuel filter bypass condition exists on the left engine. In addition, a status-level L ENG FUEL FILT message shows on the EICAS Status page. The STATUS Cue indication appears anytime a new status message exists with the EICAS Status page not displayed.
Boeing has been notified by the Federal Aviation Administration (FAA) Aircraft Certification Office (ACO) that an Immediate Adopted Rule (IAR) is being drafted, which will result in imminent issuance of an Airworthiness Directive (AD) regarding this missing advisory-level message.
In the interim period with EICAS OPS Version 6 installed, the following temporary operating instructions are provided:
If the STATUS Cue shows anytime on the ground after engine start or during flight, select the Status Page on the secondary EICAS display, and verify the "L ENG FUEL FILT" message is not shown. If the "L ENG FUEL FILT" message is not shown on the Status Page, the secondary engine parameters may be reselected on the secondary EICAS display, or the display may be blanked. If the "L ENG FUEL FILT" message is shown on the Status Page, accomplish the ENGINE FUEL FILTER non-normal checklist as published in the Boeing Quick Reference Handbook (QRH). If on the ground, check the Dispatch Deviations Guide (DDG), or operator equivalent.
In the unlikely event the status-level "L ENG FUEL FILT" and advisory-level "R ENG FUEL FILT" messages are simultaneously shown, an impending fuel filter bypass condition exists on both engines. With both messages shown, airplane fuel system contamination may be present and may result in erratic engine operation and flameout.
Further flight crew action in response to either or both the "L ENG FUEL FILT" status-level message and the "R ENG FUEL FILT" advisory-level messages being shown are not established by Boeing or the FAA. Any further flight crew action should be determined by individual operator policy.
Boeing policy on flight crew use of status-level messages has not changed. After engine start, any condition having adverse effect on safe continuation of the flight appears as an EICAS alert message (Warning, Caution, or Advisory). If other status-level messages are shown as a consequence of complying with these temporary operating instructions, the flight crew should respond in accordance with the appropriate operator policy.
On airplanes with EICAS OPS Version 6 installed, the effects of this Flight Crew Operations Manual Bulletin are immediately corrected by incorporation of EICAS OPS Version 5 by either of the following applicable actions:
Boeing has directed Rockwell Collins to develop an EICAS software modification to correct the missing EICAS alert message logic in EICAS OPS Version 6. This Flight Crew Operations Manual Bulletin will be revised to include the Service Bulletin information of the future EICAS OPS Version modification when available.
This Flight Crew Operations Manual Bulletin will be "Cancelled" (CANC) upon operator notification to Boeing that all affected airplanes covered in this Flight Crew Operations Manual have been modified replacing EICAS OPS Version 6. EICAS OPS Version 6 can be replaced either by the applicable action listed above, or by incorporation of the future EICAS OPS Version, when available.