PLT OF C150 DOING NIGHT TRAINING HAS ROTOR WASH ENCOUNTER FROM 2 H53 HELIS ALSO DOING TOUCH AND GOES IN THE TFC PATTERN.

Narrative

WHILE CONDUCTING CURRENCY NIGHT LNDGS AT CPK; I ENCOUNTERED THE ROTOR WASH FROM 2 H53'S ON SHORT FINAL CAUSING A GAR. AFTER MY FIRST LNDG; I WAS DOWNWIND WHEN A MIL HELI CALLED ENTERING THE PATTERN '1 MI ON BASE FOR RWY 23.' I DID NOT SEE THE TFC AND CALLED THE MIL HELI ASKING POS. THE MIL HELI RPTED A FLT OF 2 ON FINAL. I THEN PICKED THEM UP VISUALLY. ALL I SAW WAS 2 STEADY RED LIGHTS ABOUT 100 FT APART. I DID NOT SEE A FLASHING LIGHT/BEACON; OR STROBE. AS I APCHED ABEAM THE END OF RWY 23; THE HELIS WERE ON SHORT FINAL. SINCE I FIGURED THEY WOULD BE ON THE GND FOR A WHILE (HELI INDICATED THEY INTENDED TO DO 'CLOSED TFC'); I EXTENDED DOWNWIND; CALLED TURNING BASE AND FINAL. ON SHORT FINAL; AT ABOUT 100 FT MSL; I EXPERIENCED SEVERE TURB. THE C150 WENT INTO AN UNCOMMANDED 30 DEG BANK WITH SEVERE BUFFETING. I IMMEDIATELY DID A GAR. I THEN CALLED THE MIL HELI TO ASK WHAT TYPE; INFORMING THE PLT I HAD ENCOUNTERED SEVERE WASH. THE MIL HELI INFORMED ME THEY WERE 2 H53'S WHICH I BELIEVE IS THE LARGEST; HEAVIEST HELI IN THE MIL INVENTORY. ON THE NEXT PASS; I EXTENDED 2 MI UPWIND WHILE THE H53'S MADE ANOTHER LNDG. I AGAIN HAD TO ASK FOR THE HELI'S POS SINCE A BEACON/STROBE WAS STILL NOT VISIBLE TO ME. THE H53'S THEN TAXIED OFF THE ACTIVE AND REMAINED THERE UNTIL I COMPLETED SEVERAL MORE LNDGS AND TAXIED BACK TO THE PARKING AREA. THE 2 H53'S THEN TOOK OFF AND DEPARTED. THE HAZARDS I SEE IN THIS INCIDENT ARE: 1) MIL H53'S NOT USING PROPER UNCTLED ARPT ENTRY/PATTERN PROCS/VOICE PROCS (I BELIEVE THAT IF HELIS ARE USING THE FIXED WING PATTERN THEY HAVE TO COMPLY). 2) POSSIBLY CONDUCTING NIGHT FORMATION/LNDG TRAINING WITHOUT A BEACON VISIBLE. 3) MIL H53 NOT ANNOUNCING THAT THEY WERE H53'S OR 'HVY.' BEING A RETIRED MIL PLT; I BELIEVE IT WOULD BE BENEFICIAL TO SAFETY IF MIL PLTS; USING UNCTLED ARPTS FOR TRAINING; COMPLY STRICTLY WITH UNCTLED ARPT PROCS IN THE AIM -- AND IF THEY'RE HVY; THEY ADD IT TO THEIR VOICE CALLS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT HE WAS UNAWARE OF THE SIZE OF THE HELIS AND WOULD HAVE LEFT MUCH GREATER SEPARATION HAD HE BEEN AWARE. HE WOULD HAVE IMMEDIATELY MADE A GAR HAD THEY ANNOUNCED THEIR TYPE. HE FEELS STRONGLY THAT IT IS IMPORTANT AT NIGHT FOR TFC TO ANNOUNCE POS AND TYPE OF EQUIP. HE HAD TROUBLE LOCATING THE HELIS SINCE HE COULD NOT SIGHT A ROTATING BEACON. APPARENTLY HIS COM INDICATING HE HAD TO MAKE THE GAR DUE TO THE TURB ENCOUNTER CAUSED THE HELI PLTS TO PARK AND WAIT FOR HIM TO COMPLETE HIS LNDGS. HE WAS COMPLETING HIS NIGHT CURRENCY REQUIREMENT AND MADE HIS 3 LNDGS AFTER THE GAR.