Date: 201909
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Fuel Quantity-Pressure Indication
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Troubleshooting; Communication Breakdown; Other / Unknown
Second reporter function: Captain; Pilot Flying
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate
Result: General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft; Human Factors; MEL; Procedure
Primary problem: MEL

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.


Second narrative: Received a plane swap into an aircraft with inop left/center/total fuel readouts with the MEL XX-XX-XX. Half way through fueling the right wing we lost the right indication. I immediately called Maintenance telling them this MEL doesn't apply anymore. He sternly said it is written up for all readouts to be inop and we do not need another write up and signed the plane back into service. Looking at the MEL headline it does say 'left/right/ and total' can be inop; which is what we were going off of. But after landing in ZZZ1; I called MX to run through the MLI readings chart. He asked about my right fuel which I told him MX said we were okay with the current MEL. He stated no; and upon further reading we realized we missed a portion of the MEL that stated only one side can be inop only.  New airplane with tight turn lead to rushing of the crew; which lead to misreading of the current MEL. Slowing down more even if it is a delayed flight; read carefully through the MEL's don't follow just the headline for guidance.


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