DURING TAKEOFF; HOME-BUILT VANS RV-9A PILOT NOTICES THE SUBARU ENGINE RPM'S AND THE MT PROPELLER RPM'S HAD REDLINED. PILOT DECLARED EMERGENCY SHORTLY AFTER SMELLING ENGINE BURNING. NORMAL LANDING; NO PROP OR ENGINE DAMAGE.

Narrative

MY AIRCRAFT IS EQUIPPED WITH AN ELECTRICALLY ADJUSTABLE CONSTANT SPEED PROPELLER MANUFACTURED BY MT; AND A SUBARU 2.5L AUTO CONVERSION ENGINE. THE ENGINE DRIVES A 2:1 SPEED REDUCTION UNIT TO ACHIEVE MAXIMUM POWER WITHOUT EXCEEDING THE PROPELLER REDLINE OF 2700 RPM; WHICH MEANS NORMAL ENGINE REDLINE IS ABOUT 5400 RPM. AFTER A NORMAL PRE-FLIGHT AND ENGINE RUN UP; WHICH INCLUDES VERIFYING PROPELLER CONTROL; I RECEIVED CLEARANCE TO TAXI TO THE RUNWAY. THE INTENT OF THE FLIGHT WAS TO PRACTICE TOUCH AND GO LANDINGS. I CALLED THE TOWER FOR CLEARANCE TO REMAIN IN CLOSED TRAFFIC FOR TOUCH AND GO'S. I EVENTUALLY RECEIVED A TAKEOFF CLEARANCE WITH INSTRUCTIONS TO MAINTAIN UPWIND 'TO THE RIVER BED' TO AVOID INBOUND TRAFFIC. I ALSO KNEW THE NEXT ACFT IN LINE FOR TAKEOFF WAS A LEAR JET AND THAT THERE WAS OTHER TRAFFIC IN THE PATTERN. THERE WAS QUITE A LOT OF NORMAL RADIO CHATTER BETWEEN ATC AND THE OTHER ACFT. I TAXIED ONTO THE RWY AND APPLIED FULL THROTTLE WITH THE PROP CTLR SET TO 2700 RPM; WHICH IS THE PROC FOR NORMAL FULL POWER TAKEOFF. ONCE AIRBORNE; THE PROP IS ABLE TO TURN FASTER; AND NORMALLY THE ELECTRONIC CONTROLLER INCREASES THE BLADE PITCH TO MAINTAIN 2700 RPM. THE PROP HUB IS RELATIVELY SLOW TO RESPOND; SO IT IS NOT UNUSUAL TO QUICKLY ACHIEVE THE REDLINE PROP RPM. I THEN NOTICED AN ENGINE ALARM FROM MY GRT EIS 4000 ENGINE MONITOR INDICATING EXCESSIVE RPM. I IMMEDIATELY TURNED THE PROP CONTROLLER TO 2500 RPM AND REDUCED POWER SLIGHTLY TO ALLOW THE PROP HUB TO 'CATCH UP' WITH ADJUSTING THE BLADE PITCH. AS THIS IS NOT AN UNUSUAL SITUATION; I DIDN'T WORRY ABOUT IT AND CONTINUED TO CLIMB OUT. A FEW SECONDS LATER; THE ENGINE WAS WOUND UP TO ITS ABSOLUTE REDLINE OF 6800 RPM; WHICH IS ABOUT 3380 PROP RPM. THIS IS FAR IN EXCESS OF THE SAFE OPERATIONAL LIMIT OF THE PROPELLER. I IMMEDIATELY REDUCED THROTTLE TO MAINTAIN 2700 PROP RPM. DATA LOG ANALYSIS SHOWS THAT THE THROTTLE POSITION WAS MOVED TO 43% OF MAXIMUM THROTTLE TO MAINTAIN 2700 RPM. THE EFFECT OF THIS WAS THAT THE AIRCRAFT WAS UNABLE TO CLIMB AT MORE THAN ABOUT 100 FPM ON THE UPWIND DEP LEG. BECAUSE OF THE UNUSUALLY LOW POWER SETTING; I DECIDED NOT TO ATTEMPT ANY DIAGNOSIS OF THE PROBLEM; BUT RATHER TO DEVOTE MY ATTENTION TO MAINTAINING CONTROL OF THE AIRPLANE IN THE STATE IT WAS IN. WHILE THE SITUATION WAS OBVIOUSLY SERIOUS; I KNEW I COULD MAKE IT AROUND THE PATTERN AND LAND WITHOUT ENDANGERING OTHER AIRCRAFT. THE AIRPLANE HAS AN ABUNDANCE OF POWER; AND EVEN AT LESS THAN 1/2 THROTTLE I WAS ABLE TO EASILY MAINTAIN ALTITUDE AND FULL CONTROL. HOWEVER; I ALSO WANTED TO MAKE SURE ATC WAS AWARE THAT I NEEDED PRIORITY. SO HERE IS THE EXCITING PART. THERE WAS SO MUCH RADIO TRAFFIC I WAS UNABLE TO GET A WORD IN UNTIL WELL INTO THE SITUATION. BY THIS TIME I TURNED ONTO A RIGHT CROSSWIND LEG; BUT WELL SHORT OF THE RIVER BED. I WAITED SEVERAL SECONDS FOR A BREAK IN RADIO TRAFFIC. IN RETROSPECT; I SHOULD HAVE IMMEDIATELY SAID 'EMERGENCY -- UNABLE TO MAKE POWER' OR SOMETHING NICE AND SIMPLE TO THE POINT. INSTEAD; I SAID SOMETHING LIKE 'PAN PAN PAN; (CALLSIGN) HAS PROP CONTROLLER FAILURE. NOT MAKING MUCH POWER; TURNED EARLY FOR RIGHT TRAFFIC; WILL BE FULL STOP RUNWAY XX' WHICH TOOK TOO MANY SECONDS OF PRECIOUS TIME TO SPEAK WHILE DISTRACTED WITH A CRITICAL SITUATION IN THE COCKPIT. ATC TOOK MY SPEECH TO MEAN THAT I HAD AN EMERGENCY; AND BEGAN A FLURRY OF RADIO CALLS TO HAVE THE LEAR JET BEHIND ME ABORT TAKEOFF AND TO REDIRECT OTHER TRAFFIC IN THE PATTERN. WHILE THIS WAS HAPPENING; I STARTED TO SMELL THE ENGINE BURNING FROM THE EXCESSIVELY HIGH POWER RUN AND I WAS SUDDENLY HIGHLY MOTIVATED TO DECLARE THE EMERGENCY AND TURN BACK TO RUNWAY YY. RIGHT AT THAT TIME; ATC CLEARED ME FOR RUNWAY YY AND I TURNED DIRECT TO THE NUMBERS; MORE THAN WILLING TO TAKE THE SHORT APPROACH. I WAS ALREADY ON A RIGHT CROSSWIND LEG; SO I TURNED RIGHT AND SAID 'TURNING DIRECT RUNWAY YY'. THE LEARJET PILOT WAS ABLE TO ABORT AND EXIT THE RUNWAY BEFORE I GOT TO THE RUNWAY AND I MADE A RELATIVELY NORMAL LANDING ON RUNWAY YYAND EXITED AT TXWY. NO DAMAGE WAS DONE TO THE PROP OR ENGINE. INSPECTION OF THE PROP HUB SHOWED EXCESSIVELY DARKENED SLIP RINGS; WHICH MAY HAVE CONTRIBUTED TO A POOR ELECTRICAL CONNECTION. CONCLUSIONS: 1. PRE FLIGHT CHECKS CONFIRMED CORRECT OPERATION OF THE CONTROLLER; BUT IT IS ENTIRELY POSSIBLE THAT THE ELECTRICAL SLIP RING CONTACT MAY HAVE BEEN MARGINAL DUE TO CARBON BUILDUP OR CORROSION; AND THE STRESS OF FULL IN FLIGHT POWER PREVENTED CORRECT OPERATION. CLEANING OF THE BRUSH/SLIP RING SYSTEM WILL NOW BE MADE AT LEAST TWICE PER YEAR INSTEAD OF JUST DURING THE AIRCRAFT ANNUAL CONDITION INSPECTION. 2. IN HINDSIGHT; I AM OF THE OPINION THAT LACK OF PRACTICE IN EMERGENCY PROCEDURES CAUSED SOME MILD PANIC. THAT; ALONG WITH THE RELUCTANCE TO SAY THE WORD 'EMERGENCY' CAUSED ME TO FAIL TO CONVEY THE SITUATION TO ATC IN A CLEAR AND CONCISE MANNER. PRACTICING EMERGENCY SCENARIOS WILL BE #1 ON MY LIST OF THINGS TO DO.