Narrative:

While conducting currency night lndgs at cpk, I encountered the rotor wash from 2 H53's on short final causing a go around. After my first landing, I was downwind when a military helicopter called entering the pattern '1 mi on base for runway 23.' I did not see the traffic and called the military helicopter asking position. The military helicopter reported a flight 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 approached abeam the end of runway 23, the helicopters were on short final. Since I figured they would be on the ground for a while (helicopter indicated they intended to do 'closed traffic'), I extended downwind, called turning base and final. On short final, at about 100 ft MSL, I experienced severe turbulence. The C150 went into an uncommanded 30 degree bank with severe buffeting. I immediately did a go around. I then called the military helicopter to ask what type, informing the pilot I had encountered severe wash. The military helicopter informed me they were 2 H53's which I believe is the largest, heaviest helicopter in the military inventory. On the next pass, I extended 2 mi upwind while the H53's made another landing. I again had to ask for the helicopter's position 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) military H53's not using proper uncontrolled airport entry/pattern procedures/voice procedures (I believe that if helicopters are using the fixed wing pattern they have to comply). 2) possibly conducting night formation/landing training without a beacon visible. 3) military H53 not announcing that they were H53's or 'heavy.' being a retired military pilot, I believe it would be beneficial to safety if military pilots, using uncontrolled airports for training, comply strictly with uncontrolled airport procedures in the aim -- and if they're heavy, they add it to their voice calls. Callback conversation with reporter revealed the following information: reporter states that he was unaware of the size of the helicopters and would have left much greater separation had he been aware. He would have immediately made a go around had they announced their type. He feels strongly that it is important at night for traffic to announce position and type of equipment. He had trouble locating the helicopters since he could not sight a rotating beacon. Apparently his communication indicating he had to make the go around due to the turbulence encounter caused the helicopter pilots to park and wait for him to complete his lndgs. He was completing his night currency requirement and made his 3 lndgs after the go around.

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Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of July 2007 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.