Date: 201506
Local time of day: 1201-1800
Flight conditions: VMC
Light: Daylight
Aircraft: Cessna 170
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Training
Flight phase: Final Approach
Airspace: Class G ZZZ
ATC / advisory: CTAF ZZZ
Aircraft component: Reciprocating Engine Assembly
Component problem: Failed
Reporter organization: Personal
Reporter function: Instructor; Pilot Flying
Reporter qualification: Air Traffic Control Fully Certified; Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Human factors: Situational Awareness; Training / Qualification
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Object; Inflight Event / Encounter Object
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew Landed in Emergency Condition; Flight Crew Took Evasive Action
Contributing factors: Aircraft; Human Factors
Primary problem: Ambiguous

Narrative: Student's first lesson with second student in backseat. After 20 minutes of taxiing instruction; we departed the airport and flew for 20 minutes; remaining within 3 miles of the departure point. Returning to land; while on final; advanced power because aircraft was low and discovered the engine had lost all power. Aircraft was beyond gliding distance to the runway so made a 20 degree right turn and landed on a paved road located just to the right of extended runway center line. Had to cross a 7 foot high fence to make the road. Cleared the fence and subsequently stalled the aircraft between 10 & 15 feet. Made hard landing on center line of road. Road had a gentle curve to the right and I was unable to keep the aircraft on the road. Aircraft went off the road on the left side; struck a 6' pine log lying on the shoulder which pulled the aircraft further left. Aircraft left wing made contact with the 7 foot fence that paralleled the road. Wing tip then made contact about 12 inches inboard of wing tip with a large wooden fence post that caused the aircraft to ground loop to the left. FAA investigation revealed a large quantity of water in the right tank & the gascolator was full of water. Subsequently discovered the right wing tank cap seal was bad. That and combination of recessed fuel caps and sitting outside for several days of rain showers explained the source of water. Extensive pre-flight of aircraft while giving 2 students instruction and drained all sumps. Did not notice that the 'fluid' drained from the right wing was all water. (Over 16 ounces of water was drained).  This was my first flight in this aircraft for new owners and preflight was during a light drizzle from a rain shower that had just passed. I did not remove or examine the fuel caps as I did not want to allow the water trapped in the cap recess to get into the tank. I noticed that the 'Fluid' from the right wing wasn't proper color but attributed this to auto fuel that had been used previously. Smelled the 'fluid' and it had the odor of Auto fuel. Obviously; when I drained the fuel sampler; I didn't notice any water droplets remaining in the sampler. I did notice on the gascolator that the fuel was blue but still had an auto fuel odor. Oddly enough; when I drained the left tank; I intentionally caught water dripping off the flap to show the students what water looked like in a fuel sampler.  Lesson learned: If it ain't BLUE; don't fly. I never liked auto fuel in aircraft anyway. Although the engine stoppage was not due to auto fuel; I don't think I would have dismissed the fuel color had I not thought auto fuel was still in the tanks.




Synopsis: Cessna 170 Instructor experiences engine stoppage beyond gliding distance from the airport and lands on a narrow road. A hard landing ensues and the aircraft cannot be kept on the road  as it curves to the right and a fence post is struck with left wingtip.