Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Troubleshooting
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Air Traffic Control Provided Assistance; Flight Crew Overcame Equipment Problem; Flight Crew Returned To Gate; Flight Crew Requested ATC Assistance / Clarification; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft; Human Factors
Upon holding short of the runway in ZZZ; we experienced a burning odor in the cockpit during the pneumatic ice protection test. We contacted Maintenance and began troubleshooting. Both packs were individually giving us a burning odor. The flight attendant had called us to let us know that he smelled it too. We then returned to the gate. Once at the gate; we submitted 2 write-ups; one for the burning odor and one for a flickering Multi-Function Flight Displays screen that was progressively getting worse. I was informed later that this plane had the same issue the month prior. After our write up; maintenance could not reproduce the problem and signed the aircraft off. I later learned; from my flight attendant who was now with the new crew on the same plane; upon engine startup; they immediately began to smell burning fumes. This was following the sign-off from maintenance. Flight crew shut down packs and taxi back to the gate.Captain recommended replacing all duct work and packs as burning odor/fumes seems to be a common issue; or find out what is causing so many similar problems.
Air Carrier Captain reported a ground gate return due to a fume event during Pneumatic Ice Test while holding for departure.