Narrative:

About 15 miles northwest of the VORTAC; southeast bound I noticed the left fuel gauge near empty. The right tank gauge showed about 1/4. The gauge needles were of course not steady; but wiggling back and forth. This seemed odd since the tanks held 62 gallons at [the departure airport] 1.5 hours previously. I switched the fuel selector from 'both' to 'right'. A couple minutes later the engine seemed like it was misfiring then quit. I applied full rich mixture and switched the selector back to 'both' and the engine resumed running but quit a couple of minutes later. This all occurred while I was being switched from approach to tower. I called mayday and searched for a safe place to land. I was about 3;000 AGL and knew I could not glide 10 plus miles to the airport. I selected a location and executed a safe emergency approach and landing on a 2;000 foot length of straight gravel road. Neither the passenger nor I were injured; nor was the aircraft damaged. I did notice that the left fuel cap was missing. Both fuel tanks were empty. We moved the aircraft off the road; [and] then were picked up by a local fire department employee who took us to the airport. There I spoke with [the airport] tower; and then with [an individual] from the FAA. The FAA representative agreed with me that the incident was not one in which a NTSB 830 report was required; and that it would be ok to obtain a fuel cap; fuel the plane; and depart from the gravel road if it was safe. Later in the day I returned to the plane with an a&P mechanic; a fuel cap; and 10 gallons of fuel. I took off and flew to the airport. Later I called the [departure airport's] FBO to see by chance [if] anyone found a fuel cap; and yes; they informed me that someone had turned in a 'monarch' fuel cap; that it was found on the taxiway somewhere between the ramp and departure runway. I therefore believe that the fuel cap was not secured adequately. During preflight I simultaneously returned sump-drain fuel while visually verifying full tanks. I do remember reattaching the fuel caps after the visual inspection. It is worth mentioning that these stc'ed 'monarch' fuel caps are quite different than standard equipment cessna fuel caps; in that they require substantially more screwing down than a simple twist.I feel a contributing factor was my relatively unfamiliarity in the use of monarch caps; I have about 650-675 hours in cessna aircraft overall; nearly 300 in cessna 182s; but only about 5.5 in this particular aircraft with these fuel caps. Obviously it is very worthwhile to check; recheck; and double-check the security of these types of fuel caps before flight. Closer attention to the fuel gauges during cruise is also suggested; so as to perform a precautionary landing at an airport if warranted.

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Original NASA ASRS Text

Title: A C182 engine quit in flight because of fuel exhaustion after the Monarch fuel caps came off during taxi because they not completely secured by the pilot who was unfamiliar with that type cap. A safe off airport landing was made.

Narrative: About 15 miles northwest of the VORTAC; southeast bound I noticed the left fuel gauge near empty. The right tank gauge showed about 1/4. The gauge needles were of course not steady; but wiggling back and forth. This seemed odd since the tanks held 62 gallons at [the departure airport] 1.5 hours previously. I switched the fuel selector from 'both' to 'right'. A couple minutes later the engine seemed like it was misfiring then quit. I applied full rich mixture and switched the selector back to 'both' and the engine resumed running but quit a couple of minutes later. This all occurred while I was being switched from Approach to Tower. I called Mayday and searched for a safe place to land. I was about 3;000 AGL and knew I could not glide 10 plus miles to the airport. I selected a location and executed a safe emergency approach and landing on a 2;000 foot length of straight gravel road. Neither the passenger nor I were injured; nor was the aircraft damaged. I did notice that the left fuel cap was missing. Both fuel tanks were empty. We moved the aircraft off the road; [and] then were picked up by a Local Fire Department employee who took us to the airport. There I spoke with [the airport] Tower; and then with [an individual] from the FAA. The FAA Representative agreed with me that the incident was not one in which a NTSB 830 report was required; and that it would be OK to obtain a fuel cap; fuel the plane; and depart from the gravel road if it was safe. Later in the day I returned to the plane with an A&P Mechanic; a fuel cap; and 10 gallons of fuel. I took off and flew to the airport. Later I called the [departure airport's] FBO to see by chance [if] anyone found a fuel cap; and yes; they informed me that someone had turned in a 'Monarch' fuel cap; that it was found on the taxiway somewhere between the ramp and departure runway. I therefore believe that the fuel cap was not secured adequately. During preflight I simultaneously returned sump-drain fuel while visually verifying full tanks. I do remember reattaching the fuel caps after the visual inspection. It is worth mentioning that these STC'ed 'Monarch' fuel caps are quite different than standard equipment Cessna fuel caps; in that they require substantially more screwing down than a simple twist.I feel a contributing factor was my relatively unfamiliarity in the use of Monarch caps; I have about 650-675 hours in Cessna aircraft overall; nearly 300 in Cessna 182s; but only about 5.5 in this particular aircraft with these fuel caps. Obviously it is very worthwhile to check; recheck; and double-check the security of these types of fuel caps before flight. Closer attention to the fuel gauges during cruise is also suggested; so as to perform a precautionary landing at an airport if warranted.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.