Incident: Instructor and student practicing gliding turns. During straight glide and approaching 1000 feet above the coast the propeller gradually slowed down over a 15 second period and stopped. Instructor transmitted Mayday and turned to ditch along side boat that was 50 yards off shore. Student petrified so instructor reached across student and attempted restart re starter key with no luck. Instructor again reached over and gave one pump at primer then tried a restart. Immediate start accomplished at 500 feet. By sheer chance the same instructor had a few weeks earlier endorsed the maintenance release for a jamming primer plunger which was rectified by an LAME
Interestingly, same aircraft with different instructor had stopped prop during lead up to practice stall recovery. Instructor dived aircraft to get prop turning and after considerable height loss was successful. Instructor should have endorsed the defect in maintenance release but elected not to do. The reason for the prop stopping lay undetected until the next time the aircraft flew and came to close to ditching.
That incident proves very little other than the engine required more fuel (on one or two cylinders) to get a start. Does that report explain where the throttle and mixture were set? Does it detail there being likely intake leaks from the primer? I suspect that the throttle was at idle (closed butterfly) and mixture full rich, the most likely combination to get a flame out besides ICO.
Having nosed over, (not at best glide), the best position for the throttle is WOT, lots of air and fuel potential and minimal restriction in the carb/fcu on the engine allowing the rpm to increase with the minimum effort.
Without the prop turning at sufficient RPM, no amount of primer is going help.
Extract from a Cessna POH
ENGINE FAILURE DURING FLIGHT (Restart Procedures)
1. Airspeed -- 65 KIAS.
2. Fuel Shutoff Valve -- ON (push full in).
3. Fuel Selector Valve -- BOTH.
4. Auxiliary Fuel Pump Switch -- ON.
5. Mixture -- RICH (if restart has not occurred).
6. Ignition Switch -- BOTH (or START if propeller is stopped).
NOTE
If the propeller is windmilling, the engine will restart automatically within a few seconds. If the propeller has stopped (possible at low speeds), turn the ignition switch to START, advance the throttle slowly from idle (assumed to be WOT)and lean the mixture from full rich as required for smooth operation.(A mixture sweep)
7. Auxiliary Fuel Pump Switch -- OFF.