Narrative:

After switching into a new aircraft due to ACARS no comm; and we immediately noticed an MEL for the fuel monitoring system (MEL xx-xx-xx). At the time of fueling; we still had the right side fuel pressure readout operating. Reading the MEL and talking with maintenance personnel; we understood our procedures and what to accomplish in order to track fuel quantity/burn in order to operate safely. Shortly before pushback; we lost the right side fuel quantity readout. Maintenance personnel were still on board. We showed them and they said we are still good to go. The captain also called maintenance control and informed them of the loss of the right side quantity fuel readout. After referencing the MEL; maintenance control said we were still good to go since the MEL references EICAS fuel tank quantity readouts (left; right; and total). We continued with our flight preparations and checklists and pushed back a few mins late. We departed the airport and landed at our destination with no issues and tracked fuel burn utilizing the FMS as instructed in the MEL. Upon landing and waiting for contract maintenance in order to refuel and comply for the return leg; the captain called maintenance control again to inquire about contract maintenance and when we should expect them. Maintenance control this time after hearing that we had now lost the right quantity indications; informed us that our aircraft was down for maintenance. Hearing this; we were surprised since it was different than we were told at our departure airport. We re-referenced the MEL and saw that it states lower in it 'one main fuel tank quantity readout plus total quantity readout may be inoperative provided)'. After reading this we realized that we should not have departed our departure airport.the cause of the event is because of human interpretation errors in a dynamic operating environment. The drive to get out on time in this environment while utilizing aircraft that are operating with aircraft that have complex MEL issues lead to human comprehension/interpretation errors. If we had returned and read/comprehended the MEL after the loss of the right side quantity indicator; we would have realized the aircraft was not suitable for operation. Ensure that we foster an environment that ensures pilots do not feel pressured to execute to quickly. As a pilot; I will ensure that I am reading and comprehending all mels in the future and re-reference even after hearing from a second source we are able to continue.

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Original NASA ASRS Text

Title: Flight crew reported that an MEL for Fuel Quantity Indication was misinterpreted by Maintenance and the aircraft was dispatched in a non airworthy condition.

Narrative: After switching into a new aircraft due to ACARS no comm; and we immediately noticed an MEL for the Fuel monitoring system (MEL XX-XX-XX). At the time of fueling; we still had the right side fuel pressure readout operating. Reading the MEL and talking with Maintenance Personnel; we understood our procedures and what to accomplish in order to track fuel quantity/burn in order to operate safely. Shortly before pushback; we lost the right side fuel quantity readout. Maintenance Personnel were still on board. We showed them and they said we are still good to go. The Captain also called Maintenance Control and informed them of the loss of the right side quantity fuel readout. After referencing the MEL; Maintenance Control said we were still good to go since the MEL references EICAS Fuel Tank Quantity Readouts (Left; Right; and Total). We continued with our flight preparations and checklists and pushed back a few mins late. We departed the airport and landed at our destination with no issues and tracked fuel burn utilizing the FMS as instructed in the MEL. Upon landing and waiting for Contract Maintenance in order to refuel and comply for the return leg; the Captain called Maintenance Control again to inquire about Contract Maintenance and when we should expect them. Maintenance Control this time after hearing that we had now lost the right quantity indications; informed us that our aircraft was down for Maintenance. Hearing this; we were surprised since it was different than we were told at our departure airport. We re-referenced the MEL and saw that it states lower in it 'One main fuel tank quantity readout plus total quantity readout may be inoperative provided)'. After reading this we realized that we should not have departed our departure airport.The cause of the event is because of human interpretation errors in a dynamic operating environment. The drive to get out on time in this environment while utilizing aircraft that are operating with aircraft that have complex MEL issues lead to human comprehension/interpretation errors. If we had returned and read/comprehended the MEL after the loss of the right side quantity indicator; we would have realized the aircraft was not suitable for operation. Ensure that we foster an environment that ensures pilots do not feel pressured to execute to quickly. As a pilot; I will ensure that I am reading and comprehending all MELs in the future and re-reference even after hearing from a second source we are able to continue.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.