B737 flight crew reported a cabin smoke event at the gate while using an air cart and gate conditioned air with an inoperative APU. The Captain refused to operate the aircraft and the crew deplaned.
Synopsis
B737 flight crew reported a cabin smoke event at the gate while using an air cart and gate conditioned air with an inoperative APU. The Captain refused to operate the aircraft and the crew deplaned.
Narrative
During preflight review of aircraft status; aircraft was noted to have a deferred APU. Gate Preconditioned Air (PCA) was connected at the time; and was not satisfactory to cool down the cabin prior to boarding. Once an external air cart was connected to the aircraft for engine start purposes; the Captain and I elected to run both packs to cool down the cabin. Almost immediately I noticed an exhaust smell; which I believed was simply fumes ingested from the ramp area. As the cabin was cooling down; Maintenance was onboard resolving a pressurization controller issue. Once Maintenance work was completed; the Captain also noticed the smell and we both decided to shut down the packs until necessary to cool down the cabin with PAX on board. Approximately 2-3 minutes after turning off the packs; the cockpit began filling with visible smoke. The Captain; Maintenance personal; and I all investigated and could not determine the source. Maintenance inspected the Electronic Equipment (E/E) Compartment with no trace of the smoke. Captain then refused the airplane; and we deplaned the aircraft without further incident. We both visited the onsite clinic and removed ourselves from duty for the rest of the day.Cause: This issue couldn't have been mitigated by ensuring the APU was operating; especially during summer months in ZZZ.
Second reporter narrative
Was in preflight preparing for our flight to ZZZ1. The APU was deferred and crew ran the packs off the air start cart for approximately 20 minutes. We had an Estimated Departure Clearance Time (EDCT) so we shut down the packs and were using only preconditioned air to cool the aircraft for the 10 minutes prior to the event. At the same time we found an issue with the pressurization control panel and called ZZZ Maintenance. A maintenance technician arrived and resolved the pressurization panel issue. As he was getting ready to leave the Captain; First Officer (FO); and AMT noticed smoke of unknown origin in the flight deck. No smoke was noticed in the passenger cabin. The maintenance technician checked the Electrical Equipment (E and E) compartment for any indication of the origin of the smoke but found none.A maintenance supervisor was called and on his arrival the Captain refused the aircraft on the basis of smoke of unknown origin. The crew left the aircraft; the cockpit crew removed themselves from any further flying this day and reported to the medical clinic at ZZZ for evaluation. Examination by the doctor on duty showed both the Captain and First Officer fit for duty and both deadheaded to their home bases that evening.Cause: Possible issues with either the air-start cart; the air conditioning packs; or Preconditioned Air (PCA).
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.