Cardinal 177/177RG
Air Traffic Control Fully Certified; Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine
Air Traffic Control Non Radar 2; Air Traffic Control Radar 24; Flight Crew Last 90 Days 170; Flight Crew Total 6975; Flight Crew Type 1256
Distraction; Situational Awareness
Aircraft Equipment Problem Critical; Inflight Event / Encounter Object
Air Traffic Control Provided Assistance; Aircraft Aircraft Damaged; Flight Crew Diverted; Flight Crew Landed in Emergency Condition; General Maintenance Action
Human Factors
I was flying between pipes on inspection; had contacted Approach and was under radar coverage. I was not on my usual route around the area. I was told to contact the Tower; and made contact with the tower. Tower issued me the current altimeter and I reported descending as I set the new altimeter I noticed I was 200 feet lower than I thought around 1100 MSL. I had reported my route to approach control and was checking the GPS to make sure I was going to proceed as I had told the controller. While my head was down I heard a WHOOSH! I've never heard that before in a plane I checked my engine instruments thought the RPM fluctuated. I looked for a place to land and thought everything's OK. Then I thought 'I wonder if I hit something; a bird?' I looked around behind the plane and continued on. I'm not sure of my altitude at this time but I think I was about 1000 MSL. I was continuing on my way to my pipe starting point when I felt a vibration in the controls. I decided a look on the ground was warranted and requested a landing. Tower cleared me for right downwind to runway 18; I was thinking how about straight in 36 when the tower asked if I had a problem. I advised I had an aerodynamic issue; and was cleared for straight in runway 36. I thanked him and proceeded straight in. Tower than asked if about fuel on board and somewhere around this time I noticed my right wingtip was gone; and advised tower. Tower advised me he was rolling the equipment; I started to say no; but realized I was having a slight rolling condition and let them come out. Not sure of the low speed control I left the flaps up and flew a faster final to a safe touchdown. Upon exiting the plane and walking around the wing I noticed much more damage than expected. The fuel vent line ripped through the top wing skin back 2 ribs. All screws were gone but one. I'm not sure what happened to cause the wingtip to depart the aircraft. Time in the air on this leg was about two and a quarter hours.
A pilot performing a pipeline inspection contacted an unknown object in-flight and observed an airframe vibration.  He elected to land at the nearby airport to access the damage.