C172G pilot has engine vibration on approach to land. Brings throttle to idle to stop vibration and ...

Narrative:

Normal descent at cruise RPM, without warning, engine mis- followed in 2-3 mins by excess vibration. Throttle pulled to idle to stop vibration. Reapplying throttle did not result in any return of rpms. Altitude permitted a straight in glide approach to runway 17 at martinsburg. My position and intentions were announced on 124.3. Tower not in operation. Uncontrolled field, no other traffic reported nor was seen during landing or while aircraft was towed from runway. Aircraft vibrated considerably as propeller windmilled to a stop on rollout. Visual inspection revealed engine oil dripping from right exhaust port and air intake filter. Partial disassembly has revealed at best 1 piston completely destroyed with metal particles distributed throughout case. This cylinder was replaced within the last yr at annual check. Engine is cont 0-300-D. Callback conversation with reporter revealed the following information: reporter aircraft is a C172G. There has been no FAA action in this incident and reporter checked with pilot group to determine there was no requirement to report to the FAA since the landing was made at an airport with no injuries or damage to the aircraft. The consensus of the maintenance check is that the valve stuck open and the piston came up and hit and broke the valve which disintegrated and sent metal particles throughout the engine. The history of the engine is that at the previous yr's annual 2 cylinders were replaced as they did not meet compression standards. In the most recent annual one of those cylinders again had low compression and was replaced again. The second cylinder is the one that failed in the air in this incident. Reporter and his partner are researching the part numbers trying to track down the information to determine if this was a bad batch of cylinders and to help others avoid such failures. In trying to see if other cylinders of this manufacturer have failed one mechanic stated that he didn't like this type of cylinder as there had been problems. Reporter indicated he would check back with us if he finds further information.

Original NASA ASRS Text

Title: C172G PLT HAS ENG VIBRATION ON APCH TO LAND. BRINGS THROTTLE TO IDLE TO STOP VIBRATION AND WAS ABLE TO MAKE A STRAIGHT IN LNDG AT ARPT. APPARENTLY A CYLINDER FAILURE.

Narrative: NORMAL DSCNT AT CRUISE RPM, WITHOUT WARNING, ENG MIS- FOLLOWED IN 2-3 MINS BY EXCESS VIBRATION. THROTTLE PULLED TO IDLE TO STOP VIBRATION. REAPPLYING THROTTLE DID NOT RESULT IN ANY RETURN OF RPMS. ALT PERMITTED A STRAIGHT IN GLIDE APCH TO RWY 17 AT MARTINSBURG. MY POS AND INTENTIONS WERE ANNOUNCED ON 124.3. TWR NOT IN OP. UNCTLED FIELD, NO OTHER TFC RPTED NOR WAS SEEN DURING LNDG OR WHILE ACFT WAS TOWED FROM RWY. ACFT VIBRATED CONSIDERABLY AS PROP WINDMILLED TO A STOP ON ROLLOUT. VISUAL INSPECTION REVEALED ENG OIL DRIPPING FROM R EXHAUST PORT AND AIR INTAKE FILTER. PARTIAL DISASSEMBLY HAS REVEALED AT BEST 1 PISTON COMPLETELY DESTROYED WITH METAL PARTICLES DISTRIBUTED THROUGHOUT CASE. THIS CYLINDER WAS REPLACED WITHIN THE LAST YR AT ANNUAL CHK. ENG IS CONT 0-300-D. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR ACFT IS A C172G. THERE HAS BEEN NO FAA ACTION IN THIS INCIDENT AND RPTR CHKED WITH PLT GROUP TO DETERMINE THERE WAS NO REQUIREMENT TO RPT TO THE FAA SINCE THE LNDG WAS MADE AT AN ARPT WITH NO INJURIES OR DAMAGE TO THE ACFT. THE CONSENSUS OF THE MAINT CHK IS THAT THE VALVE STUCK OPEN AND THE PISTON CAME UP AND HIT AND BROKE THE VALVE WHICH DISINTEGRATED AND SENT METAL PARTICLES THROUGHOUT THE ENG. THE HISTORY OF THE ENG IS THAT AT THE PREVIOUS YR'S ANNUAL 2 CYLINDERS WERE REPLACED AS THEY DID NOT MEET COMPRESSION STANDARDS. IN THE MOST RECENT ANNUAL ONE OF THOSE CYLINDERS AGAIN HAD LOW COMPRESSION AND WAS REPLACED AGAIN. THE SECOND CYLINDER IS THE ONE THAT FAILED IN THE AIR IN THIS INCIDENT. RPTR AND HIS PARTNER ARE RESEARCHING THE PART NUMBERS TRYING TO TRACK DOWN THE INFO TO DETERMINE IF THIS WAS A BAD BATCH OF CYLINDERS AND TO HELP OTHERS AVOID SUCH FAILURES. IN TRYING TO SEE IF OTHER CYLINDERS OF THIS MANUFACTURER HAVE FAILED ONE MECH STATED THAT HE DIDN'T LIKE THIS TYPE OF CYLINDER AS THERE HAD BEEN PROBS. RPTR INDICATED HE WOULD CHK BACK WITH US IF HE FINDS FURTHER INFO.

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.

Attributes
ACN	369798
Time
Date	199705
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : mrb
State Reference	WV
Altitude	msl bound lower : 557 msl bound upper : 2200
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : ont
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	descent other
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
Experience	flight time last 90 days : 2 flight time total : 300 flight time type : 250
ASRS Report	369798
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : declared emergency other
Consequence	other Other
Supplementary
Primary Problem	Aircraft

C172G pilot has engine vibration on approach to land. Brings throttle to idle to stop vibration and was able to make a straight in landing at airport. Apparently a cylinder failure.