On March 19, 1995, at 1502 eastern standard time (EST), a Piper PA-28-181, N4385M, operated as a rental airplane by Ann Arbor Flyers, Incorporated, of Ann Arbor, Michigan, impacted in a level field two miles northwest of Ann Arbor Municipal Airport (ARB), and was substantially damaged. The private pilot was uninjured, and the passenger received minor injuries. No fire occurred. Visual meteorological conditions existed at the time of the accident, no flight plan was filed. The flight originated at 1445 EST, as a 14 CFR Part 91 local pleasure flight. The pilot reported that during her preflight, the engine was being recowled after a scheduled oil change. She reported that during her engine runup, all indications were normal, but during the initial climb, ten minutes after takeoff, oil pressure dropped to zero (0). During her precautionary return to ARB, the engine began to run rough, she selected an off airport field to land in, and secured the engine. During the forced landing in an uncultivated field, the nose wheel broke off and the airplane flipped over. The mechanic who had changed the oil stated "When draining was complete an external drain tube was removed without closing the valve. Then a paper plug was inserted in the valve to avoid drips inside the cowl from the 'closed' valve. This plug prevented what should have been obvious flow thru onto the floor at the time of refill." Post crash inspection revealed the engine oil quick drain in the open position, and the bottom of the airplane covered with engine oil.