Date: 201411
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: Skylane 182/RG Turbo Skylane/RG
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Cruise
Airspace: Class D ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Fuel Tank Cap
Component problem: Improperly Operated
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Instrument; Flight Crew Private
Human factors: Other / Unknown; Situational Awareness
Anomaly: Aircraft Equipment Problem Critical; Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Fuel Issue
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Diverted; Flight Crew Landed in Emergency Condition; General Declared Emergency
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: IFR flight in VFR conditions at 4000 below clouds (5500 ceiling) the engine lost power. I immediately switched the GNS530N to nearest and pointed to ZZZ at the same time I [advised ATC] that I had engine failure. The temp was -4C so I had already pulled the carb heat then noticed that the fuel gauge on the left tank was empty and the right tank read a bit over half full. I immediately switched to the right tank but still no power. All the while I continued my glide toward ZZZ. At about 2500 feet I noticed the airport and setup for a power off landing which was uneventful with the exception of perhaps some concern to a couple who had just touched down on the runway coming from the opposite direction. I kept to the right side of the runway and landed without incident touching down with about two thirds of the runway remaining. As I coasted to a stop I moved the plane off the runway to the left side where there appeared to be a bit more room. After calling flight service on my cell phone and canceling my IFR clearance as well as notifying the briefer that I had [landed in emergency conditions] and the flight had terminated at the little grass strip uneventfully. He transferred me to a more appropriate person where I provided the same details. At this time I was given a number of the TRACON which I wrote down incorrectly and decided that that could wait. Prior to the flight I had topped off the aircraft which provides more than 5 hours of flight time. As I walked from the plane to the FBO my first thought was that the fuel line from the right tank had frozen and fuel was exhausted from the left tank with plenty in the right tank. The temp on the ground was +2C so I expected that this might soon be fine once the plane warmed above freezing. I called my API and discussed with him this possibility as I walked to the FBO office. He was not convinced that this was the problem but was very helpful in getting me some assistance. When I left the locked FBO office and walked back to the plane I noticed that there was something different about the right wing gas cap. Sure enough upon close inspection it was hanging by its chain well clear of the filler port. Prior to the flight I had purchased 40 gallons of fuel (top off) that morning at my home airport and while the lineman fueled the plane I did my walk around preflight. I thought I had done a very good job of this but looking back if I had done the walk around after the refueling I would have seen the fuel caps condition and prevented this. That assumes that the lineman had not installed the fuel cap. I just need to always check the fuel and caps for every flight. I could say that this was caused by the lineman not replacing the fuel cap but in the end it is my responsibility to manage all aspects of the flight and checking the oil filler cap and the fuel caps fall under that as well. I also had a second chance to discover the missing cap since I flew to an intermediate stop in this condition to get my dog. My friend was there as I landed so the dog was quickly placed in the plane and off we went (cap off and still unnoticed). The incident happened at about 2 hours of total flight time with this cap off and represents perhaps the time it takes for 80 gallons of fuel to either leave through the open gas cap draining across from the secure tank through the crossover tube all the while the fuel is also being consumed by the engine at about 13.4gal per hour. The cause of this forced landing is due to poor pre-flight inspection of the fuel caps and my ignoring the following indicators during the flight.1. With the cap off fuel is gushing out over the top of the wing and trailing off past the flaps. The weather was cloudy and visibility was limited but still VFR during takeoff and initial climb out. This white background would perhaps make the observation of the fuel loss less apparent but I bet if I would have looked I would have seen it.2. I did not check the caps after getting the plane topped off.3. During flight the plane appeared to me to be heavy on the right side (side without the cap). I noticed this and continually examined the slip ball and rudder trim but never understood what was making me think something was abnormal.4. I scanned the gauges but was always satisfied that the fuel was ok because the right side less than about 3/4 tank full and the gauges were never real good at showing the fuel level when it had over 3.5 hours of fuel remaining anyway. I dipped the tanks after the incident and found that both tanks were completely empty. I then called my API who was familiar with this. He explained to me that the erroneous high fuel level indication of the tank with the cap missing was caused by the empty fuel bladder bottom surface buckling. This bladder is being sucked up by the vacuum (wing lift) which also props up the fuel float sensor bar and results in the gauge indicating a high fuel level. Problem arose because of fuel cap not being installed properly. Contributing factor was my pre-flight during the fueling process and omission of the dip check normally done when not getting fuel. Unfortunately I had a second chance to see the problem but did not do a pre-flight since the airplane had not left my sight. Discovery was truly when the engine stopped. A look at the level of fuel in the Left tank prior to the engine missing would also have been helpful in identifying a problem but I did not do that until it was too late. The problem was corrected by having 18 gal of fuel delivered to the closed airport and flying 12 minutes and topping off the plane with 62 gal of 100LL. In conclusion this could have been prevented by me doing a better preflight. It was just pure luck that the exhaustion happened so close to a grass landing strip maintained in excellent condition on a day that had very little traffic and weather conditions such that made landing with the engine off seem just like another CFI directed training exercise.




Synopsis: C182 pilot learns how long his aircraft will fly starting with full tanks and one fuel cap not installed (two hours). A successful engine off landing is accomplished at the nearest airport and the problem is diagnosed.