PA-46 Malibu Meridian
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Flight Crew Last 90 Days 60; Flight Crew Total 7300; Flight Crew Type 900
Communication Breakdown; Distraction
Aircraft Equipment Problem Critical; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Flight Crew Returned To Departure Airport; General Declared Emergency
Aircraft; Human Factors
Upon reaching FL270 on a demo flight the pilot's side window cracked. The airplane was at its certified ceiling and maximum PSI. I immediately asked for lower and direct back to our departure airport. ATC cleared us direct and to descend to FL240. We were then switched to a new frequency. I was expecting something lower and didn't catch that we were only cleared to 24;000. I was focused on reducing the cabin pressure to prevent the window from coming apart.I started a rapid descent and switched frequencies. I realized when checking on I didn't remember the assigned altitude. We were already lower than FL240. I informed the Controller we had a cracked window and needed lower. ATC cleared us to 6;000 FT. I believe the cause of the deviation was due to not enough attention being paid to ATC while distracted by a potential emergency. I think better communication about our condition with a more specific request would have allowed a lower altitude quicker and prevented the deviation.
Distracted by a cracked cockpit window while at FL270; and anxious to reduce pressurization differential; the pilot of a PA-46 failed to arrest his descent at FL240 as cleared.