B757 Undifferentiated or Other Model
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Flight Crew Last 90 Days 132; Flight Crew Total 10463; Flight Crew Type 4418
Other / Unknown
Aircraft Equipment Problem Less Severe
General Release Refused / Aircraft Not Accepted
Aircraft; Manuals
During preflight set up for subject flight; we noted that the inbound defect; 'Fuel Quantity Indicating System Blank;' Left and Totalizer indicators blank; no associated EICAS messages; had not been cleared. In addition to the blank left fuel quantity indicator and blank totalizer; we noted a FUEL QTY IND status message. Maintenance Personnel entered the flight deck around that time to check the fuel quantity indicating status. They also confirmed they were working on the indicator defect; but might have to defer it due to time constraints. Subsequently; over several minutes and a few visits to the flight deck; Maintenance Personnel confirmed MEL 28XXX would be placed on the aircraft; as well as reporting the tank stick values. The Captain and I reviewed the MEL and its potential impact to our flight. The MEL OPS PLACARD is straight forward for fuel confirmation; preflight; fuel tracking and confirmation during normal operations. I became uncomfortable; however; when comparing procedure solutions for abnormal fuel scenarios. My concerns were as follows:MEL note: 'FUEL CONFIG' EICAS ADVISORY MESSAGE OR WARNING LIGHT FOR LATERAL IMBALANCE MAY BE INHIBITED. This completely removes the FUEL CONFIG QRH as a checklist option. MEL Item H: MONITOR FUEL USAGE FOR ANY UNUSUAL DECREASE IN FUEL QUANTITY AND/OR FUEL IMBALANCE. Then MEL item I. FOR OPERATIONS WITH CENTER TANK FUEL -- Item 1 regarding predicted fuel when center tanks are empty is straight forward. Item 2 regards procedures for center tank fuel exhaustion before the predicted point and that a fuel leak should be suspected. Item (A) provides six cues; any of which can be evidence of a fuel leak. They include fuel quantity decreasing abnormally; excessive fuel flow; fuel balance rate over 2;000 lbs/hr; abnormal aileron trim; visual spray from spar and up to and including engine failure. If a leak occurs on the side with the blank indicator; the cues are reduced to abnormal aileron; apparent at around 1;600 lb imbalance; fuel spray observation; or an engine failure. Of note; Maintenance reported that the tank stick values indicated a 500 lb difference. My assessment was that the discovery of a leak in a worst-case scenario by the methods above adds considerable time and unnecessary risk to addressing the emergency. Starting off with an already 500 lb imbalance added more uncertainty and concern on my part.Confirming a leak; the MEL then refers to the FM / NON-NORMALS / FUEL / LOW FUEL as follows on procedures. Referencing the 757 QRH for a Fuel Leak; the caution at step 4 can't be fully assessed since the totalizer reading is unavailable. There were no clear solutions on how to address this; or the selections in item 10 regarding the possible messages available or not available; in order to move to the next items in the checklist.Other concerns regarding fuel related abnormal checklists. The Abnormal Fuel Transfer checklist conditions are 'Fuel quantity decreasing from the left and/or right wing tank(s) with fuel remaining in the center tank.' There could be a significant delay in addressing this scenario if the leak were on the side with the blank fuel quantity.The FUEL SYS PRESS checklist references the FUEL CONFIG light. Per the MEL; this message may not be available; adding more time to realize the situation through the cues in the MEL fuel imbalance discussion and less time to properly address the emergency. FUEL X FEED - FWD/AFT. Same as above. LOW FUEL. One of the notes indicates this message could be caused by a leak. Reference discussion above regarding concerns of the scenario without the fuel quantity and totalizer indications. My Captain agreed with my assessment and contacted the [Chief Pilot] for guidance. On the fuel leak checklist; the [Chief Pilot] said he saw my points and generally agreed with my assessment regarding the MEL fuel leak and unclear QRH application in the event of a fuel abnormal situation. The [Chief Pilot] thought the totalizer value could be deduced by fuel tracking in an operations normal condition; up to the time of an abnormal situation. He also said; words to the effect; that the MEL / QRH should be clearer; even re-written; saying; obviously; that it would take basically; more time than we had. I assessed that the time to ascertain a leak from a tank on the blank fuel indicator; left in this case; would take too long and reduce the amount of time and options to land safely. Also; we could not fully complete the other noted checklists; as written; with an acceptable level of confidence and in a timely manner; adding an undue threat to the operation.Though there was general agreement with my assessment on the fuel leak checklist by my Captain and the FODM; the FODM said the MEL was legal and the captain said he would accept the new MRD when maintenance completed their actions. I removed myself from the flight as I thought the limitations in the MEL and QRH were a threat to safely completing an abnormal fuel scenario.
B757 First Officer reported refusing flight due to lack of clarity with MEL and QRH regarding fuel leak checklists.