A B90 jump aircraft pilot reported the portable GPS came loose in flight at 17;500 FT pulling the oxygen canula and ear piece out as the jumpers were preparing to go. Aircraft control was momentarily lost and the aircraft climbed above FL180.

Narrative

I was flying a skydiver aircraft to FL175 and as I approached my jump run; my GPS failed and I no longer had a signal. I had just put in 70 degrees of flaps (which gives me some extra attitude) and I turned to yell back to my Tandem Masters that they would need to 'spot' their landing site; my GPS fell from its position (suctioned to the window) and as it fell it hit my oxygen line; which ripped my oxygen canula out of my nose and the oxygen line grabbed my headset earpiece (clarity aloft - the ear bud type. I only had one ear bud in as I had pulled the right ear bud out of my ear so I could hear the Tandem Masters) and yanked that out of my ear. I'm flying and setting up for the jump run (which is a busy time). I have lost GPS; need to put my oxygen back in my nose which is now tangled in my headset ear piece which I need to get back in my ear when the Tandem Masters yell 'go-around.' So now I'm 'going around' for another approach to a jump run so I'm putting my oxygen back on; placing my headset earpiece back in my ear and holding my GPS that has fallen from the windshield and is tangled in my oxygen line. (If I release it; it yanks at the oxygen line); and ATC notifies me that I'm above FL180 and I correct my altitude. I asked for the altimeter setting and promptly corrected. In the future my GPS will not be mounted on the windshield. I will use the yoke mount which will ensure a secure position from which the GPS unit cannot fall.