Cessna; 172S; Missing Alt-Air Door Spring; ATA 7600

Climbing to 8,000 feet, a pilot noticed a power loss and engine surging at two different times. During a phase-1 inspection, a mechanic observed the alternate-air door stuck in the open position. Further scrutiny revealed the spring (P/N 0550361-25) assisting the door was missing from the hinge assembly. The controlling servo was inspected for damage and the possible presence of the missing spring - neither was evident. This mechanic feels the alternate-air system “...is weak and needs to be improved.”

Part Total Time: 743.1 hours.