Narrative:

Report is due to flight and cabin crew operating flight XXX to ZZZ; deadhead to ZZZ1; overnight and operating flight following morning back to ZZZ. Flight crew reported to maintenance a squeal in the cabin during deadhead to ZZZ1. Line maintenance arrived to investigate and requested flight crew to start engines with [main cabin] door shut. After listening in the cabin at normal pressure levels on the ground; maintenance put aircraft pressurization system into manual mode and descended the cabin until reaching 3.0 psi and back to unpressurized; approximately 15 minutes. Crew experienced uncomfortable ear pressure but no other medical concerns. Maintenance tightened a connection in pack-1 and aircraft returned to service. In ZZZ; the following morning; captain obtained a copy of the maintenance procedures including the bold warning about non-essential personnel not being onboard. This pressurization took the flight crew to a cabin altitude below sea level; there is concern similar to a scuba dive. Pressurization and flight at altitude may not have been advisable. Company medical was called; but by this time it was 24 hours past the pressurization event. The flight attendant; who has a hearing impairment and wears hearing aids; reported being more plugged up than usual and was removed at company medical doctor's request. The flight crew unaware pressurization to 3.0 psi was planned. Line maintenance did not have copy of procedure with them. Flight crew unaware of potential hazard due to no briefing from maintenance personnel and no written copy of maintenance procedure. Ensure that when procedures are communicated from maintenance control to line maintenance; that warnings are transmitted. Provide written guidance on flight crew assisting maintenance or provide adequate personnel to perform procedure without any assistance from flight crew.

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Original NASA ASRS Text

Title: A Contract Mechanic was directed by Maintenance Control to pressurize the cabin of an EMB-145 aircraft to below sea level in the manual mode. Flight crew and Flight Attendant were not made aware after being requested to start engines with the main cabin door closed. Uncomfortable ear pressure was experienced. Crew departed in the morning; but pressurization and flight at altitude may not have been advisable due to scuba dive effect.

Narrative: Report is due to Flight and Cabin Crew operating flight XXX to ZZZ; deadhead to ZZZ1; overnight and operating flight following morning back to ZZZ. Flight Crew reported to Maintenance a squeal in the cabin during Deadhead to ZZZ1. Line Maintenance arrived to investigate and requested Flight Crew to start engines with [Main Cabin] door shut. After listening in the cabin at normal pressure levels on the ground; Maintenance put aircraft pressurization system into manual mode and descended the cabin until reaching 3.0 psi and back to unpressurized; approximately 15 minutes. Crew experienced uncomfortable ear pressure but no other medical concerns. Maintenance tightened a connection in Pack-1 and Aircraft returned to service. In ZZZ; the following morning; Captain obtained a copy of the Maintenance procedures including the BOLD WARNING about non-essential personnel not being onboard. This pressurization took the flight crew to a cabin altitude below sea level; there is concern similar to a scuba dive. Pressurization and flight at altitude may not have been advisable. Company Medical was called; but by this time it was 24 hours past the pressurization event. The flight attendant; who has a hearing impairment and wears hearing aids; reported being more plugged up than usual and was removed at Company Medical Doctor's request. The Flight Crew unaware pressurization to 3.0 psi was planned. Line Maintenance did not have copy of procedure with them. Flight Crew unaware of potential hazard due to no briefing from Maintenance personnel and no written copy of maintenance procedure. Ensure that when procedures are communicated from Maintenance Control to Line Maintenance; that warnings are transmitted. Provide written guidance on Flight Crew assisting Maintenance or provide adequate personnel to perform procedure without ANY assistance from Flight Crew.

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.