This bulletin informs flight crews of the potential for fuel pump damage that could create a potential ignition source and provides additional information and alternate operating instructions for flight crews. This revision provides Federal Aviation Administration (FAA)-approved alternate flight crew operations procedures granted under the provisions of FAA Letter 140S-04-03: "Alternative Method of Compliance (AMOC) to Airworthiness Directive 2001-15-08," dated March 1, 2004.
An operator removed a center tank fuel pump and found a damaged inlet diffuser assembly. Diffuser assembly damage may cause metal-to-metal contact, creating a potential ignition source. Ignition of fuel vapours may occur if the damaged pump is not fully immersed in fuel. Approximately 500 kilograms (1000 pounds) of fuel is required to ensure the center tank pumps remain completely immersed in fuel.
Pump damage may be accompanied by tripping of the fuel pump circuit breakers.
Center tank pump inlet diffuser damage has been the subject of FAA Airworthiness Directives. The AD’s required inspection and replacement of affected fuel pumps, and incorporation of pump improvements per Boeing Service Bulletin SB 767-28-0046. The damaged pump in a reported event had the equivalent of this Service Bulletin incorporated.
Selecting the center tank fuel pumps off before the center tank fuel quantity falls below 500 kilograms (1000 pounds) or at the first indication of low pump pressure, whichever occurs first, ensures that fuel vapours will not come in contact with a potentially damaged fuel pump. The first indication of fuel pump low pressure is the brief, intermittent illumination of the pump PRESS light before the tank quantity indicates zero. EICAS delays the CTR L or R FUEL PUMP messages until the PRESS lights illuminate continuously.
The FUEL CONFIG Light illuminates and the FUEL CONFIG advisory message appears when the center tank fuel pump switches are OFF with greater than 500 kilograms (1200 pounds) in the center tank. Flight crews may experience the FUEL CONFIG light and EICAS message appearing after the center tank fuel pump switches are selected OFF.
A scavenge system (as installed), operating with fuel pressure from the main (wing) tank pumps, will operate automatically to transfer any remaining fuel in the center tank to the main tanks. Fuel transfer begins when the main tanks are approximately half empty.
If the center tank fuel pumps are on during takeoff, a minimum of 2,300 kilograms (5000 pounds) must be in the center tank when the entry doors are closed with the airplane readied for initial taxi. This quantity should reduce the need for flight crews to select center tank pump switches off below 10,000 feet.
If one center tank fuel pump fails with ample fuel in the center tank, the failed pump should be selected OFF. The crossfeed valve(s) should be opened to prevent a fuel unbalance. The remaining center tank pump can remain ON until the center tank fuel quantity approaches 500 kilograms (1000 pounds).
There are no changes to the Fuel Jettison (as installed) or the Low Fuel Non-normal Procedures.
The following Boeing All Operators telegraphic messages were issued on this subject:
Boeing submitted request for AMOC to the Seattle Aircraft Certification Office (SACO) and Aircraft Evaluation Group (AEG) of the FAA Northwest Region Branch. The FAA has approved all provisions of the Boeing requested AMOC, per FAA Letter 140S-04-3, “Alternative Method of Compliance to Airworthiness Directive 2001-15-08,” dated March 1, 2004. The Operating Instructions section of this Operations Manual Bulletin delineates the alternate flight crew operating procedures to those contained in AD 2001-15-08.
IMPORTANT: Operator adoption of the alternate flight crew operations procedures granted under the AMOC is contingent upon operator notification of the AMOC requirements and operational approval from the Principal Operations Inspector (POI). Since most airplanes affected by this Operations Manual Bulletin are not operated under United States registry, the FAA-approved AMOC has no authority. Final approval for all airplanes operated under foreign government registry must be granted by the appropriate government regulatory authority.
If the center tank fuel pumps are on during takeoff, a minimum of 2,300 kilograms (5000 pounds) must be in the center tank when the entry doors are closed with the airplane readied for initial taxi.
As the center tank approaches empty during normal use, select both center tank fuel pump switches OFF with the first occurrence of any of the following:
If the Fuel Jettison Non-normal Procedure is being used to empty the center tank, complete the jettison procedure and select the center tank fuel pump switches to OFF when the CTR L FUEL PUMP or CTR R FUEL PUMP EICAS messages are observed or as soon as either of the center tank fuel pump PRESS lights illuminate.
If a center tank fuel pump fails with ample fuel in the center tank, accomplish the FUEL PUMP Non-normal Procedure.
The intent of the following alternate operating procedures is to provide identical 767 center tank fuel pump operating procedures to those recently mandated by FAA AD on the 757 airplane. The following are 767 alternate flight crew operating procedures approved by FAA AMOC:
Center tank fuel pump operation. The center tank fuel pump switches must be selected ON if center tank fuel quantity is 5,000 pounds (2,300 kilograms) or greater with the airplane readied for initial taxi.
Both center tank fuel pump switches must be OFF for takeoff and initial climb if center tank fuel is less than 5,000 pounds (2,300 kilograms) with the airplane readied for initial taxi. Both center tank fuel pumps should be selected ON above 10,000 feet MSL or after the pitch attitude has been reduced to begin acceleration to climb speed, if more than 1,000 pounds (500 kilograms) of fuel remains in the center tank.
Both center tank fuel pump switches must be selected OFF when center tank fuel quantity reaches approximately 1,000 pounds (500 kilograms). For airplanes not equipped with a center tank scavenge system, this 1,000 pounds (500 kilograms) of fuel may only be used in a low fuel situation.
Note: In cruise flight, center tank fuel may be reduced to approximately 800 pounds (400 kilograms) as necessary to extinguish the amber FUEL CONFIG light and “FUEL CONFIG” alert message on EICAS. This will allow the fuel configuration alert to activate for a fuel imbalance condition.
Non-normal checklist considerations. The amber FUEL CONFIG light will illuminate and the FUEL CONFIG alert message will display on EICAS with approximately 1,200 pounds (600 kilograms) of fuel quantity in the center tank and the center tank fuel pump switches are selected OFF. Do not accomplish the FUEL CONFIGURATION non-normal checklist prior to or during takeoff with less than 5,000 pounds (2,300 kilograms) of fuel in the center tank, unless an imbalance is noticed between the main tanks.
If the amber FUEL CONFIG light illuminates and the LOW FUEL alert message displays on EICAS, accomplish the LOW FUEL non-normal checklist, as published. All center tank fuel may be used regardless of the amount of fuel remaining in the center tank.
If a center fuel tank pump amber PRESS light illuminates and the CTR L,R FUEL PUMP alert message displays on EICAS with fuel in the center tank, accomplish the FUEL PUMP non-normal checklist, as published. A fuel pump failure should be assumed in this situation.
If fuel jettison operation is required, accomplish the FUEL JETTISON non-normal checklist, as published. All center tank fuel is available for jettison operations, as allowed under AD 2001-15-08.
Increase in certified Maximum Zero Fuel Weight (MZFW). Provided the affects of airplane center-of-gravity (CG) are verified to be within allowable limits, the zero fuel weight of the airplane plus the weight of fuel in the center tank may exceed the certified MZFW up to a value of 5,000 pounds (2,300 kilograms). This MZFW increase is to allow for center tank fuel, which cannot be used during takeoff and initial climb. The magnitude of the increase in zero fuel weight is not to exceed the weight of loaded fuel in the center tank and is only permitted when operating under the Airplane Flight Manual (AFM) revisions mandated by AD 2001-15-08.
This condition is corrected by Boeing Service Bulletin 767-28-0062. This bulletin will be canceled after Boeing is notified that all affected airplanes in your fleet have been modified.