Emergency declared due to very rough engine.

Attributes
ACN	82732
Time
Date	198802
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : lns
State Reference	PA
Altitude	msl bound lower : 2500 msl bound upper : 2500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : lns
Operator	general aviation : personal
Make Model Name	Small Aircraft
Flight Phase	cruise other
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private pilot : instrument
Experience	flight time last 90 days : 10 flight time total : 980 flight time type : 880
ASRS Report	82732
Person 2
Function	controller : local
Qualification	controller : non radar
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	flight crew : declared emergency other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft

Narrative:

On a VFR flight from phl to reedsville mifflin co our engine began to suddenly run rough, I tried the procedures on my emergency checklist, mags, carburetor heat, change tanks, boost pump set. At full power I could maintain altitude and 92 KTS airspeed. I called lancaster tower and notified them of my problem and they called reading ATC and got a transponder code for me to squawk. With this I was informed that I was 12 mi southeast of lancaster airport. This was also the VOR I was tracking to. I told the tower our oil pressure was ok and oil temperature was not climbing, but I thought I lost a valve and our engine was hammering pretty badly. At 6 mi out lancaster checked on my forward visibility. I told them with the sun in my face I couldn't see anything beyond a mile. They turned the runway lights up and cleared me for a straight in on runway 26. I didn't want to descended to a lower altitude until I had the runway in sight, so at about 1 mi out and then over the end of runway 26 I told the tower I was going to make a descending right turn to final and landed. The #3 cylinder was found to have no compression and a broken exhaust valve. There was no piston damage and no oil loss. I called the tower and thanked them for all their help.

Original NASA ASRS Text

Title: EMERGENCY DECLARED DUE TO VERY ROUGH ENGINE.

Narrative: ON A VFR FLT FROM PHL TO REEDSVILLE MIFFLIN CO OUR ENG BEGAN TO SUDDENLY RUN ROUGH, I TRIED THE PROCS ON MY EMER CHKLIST, MAGS, CARB HEAT, CHANGE TANKS, BOOST PUMP SET. AT FULL PWR I COULD MAINTAIN ALT AND 92 KTS AIRSPD. I CALLED LANCASTER TWR AND NOTIFIED THEM OF MY PROB AND THEY CALLED READING ATC AND GOT A TRANSPONDER CODE FOR ME TO SQUAWK. WITH THIS I WAS INFORMED THAT I WAS 12 MI SE OF LANCASTER ARPT. THIS WAS ALSO THE VOR I WAS TRACKING TO. I TOLD THE TWR OUR OIL PRESSURE WAS OK AND OIL TEMP WAS NOT CLBING, BUT I THOUGHT I LOST A VALVE AND OUR ENG WAS HAMMERING PRETTY BADLY. AT 6 MI OUT LANCASTER CHKED ON MY FORWARD VIS. I TOLD THEM WITH THE SUN IN MY FACE I COULDN'T SEE ANYTHING BEYOND A MILE. THEY TURNED THE RWY LIGHTS UP AND CLRED ME FOR A STRAIGHT IN ON RWY 26. I DIDN'T WANT TO DESCENDED TO A LOWER ALT UNTIL I HAD THE RWY IN SIGHT, SO AT ABOUT 1 MI OUT AND THEN OVER THE END OF RWY 26 I TOLD THE TWR I WAS GOING TO MAKE A DSNDING RIGHT TURN TO FINAL AND LANDED. THE #3 CYLINDER WAS FOUND TO HAVE NO COMPRESSION AND A BROKEN EXHAUST VALVE. THERE WAS NO PISTON DAMAGE AND NO OIL LOSS. I CALLED THE TWR AND THANKED THEM FOR ALL THEIR HELP.

Data retrieved from NASA's ASRS site as of August 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.