Narrative:

On jun/sun/95, I filed on IFR flight plan from idi (indiana county/jimmy stewart airport) in PA to blm, allaire airport, nj. WX was cavok with a light west breeze. I departed runway 28 and turned east toward tyrone (ton) VOR. Climbing through 3000 ft I noted a mild buffeting. I checked the flaps up, engine instruments, etc. Everything appeared normal. I elected to return to idi to check the exterior of the aircraft and ZOB gave me a heading back to the field. At the time I was 3-4 mi east of idi. As I slowed and pulled the power back the buffeting ceased and everything seemed normal. At this juncture I almost opted to continue the flight to blm but thought better of it. I told ZOB that idi was in sight and to cancel my IFR flight plan, which they did. Landing and taxi in was normal. I accomplished another magneto check, 'exercised' the propeller, checked and re-checked the instruments, pressures, vacuum, etc. All indications were normal. Upon parking I accomplished a meticulous walk-around of the aircraft. Nothing untoward was discovered. I was about to advise my passenger that I was going to cancel our trip home when one of them informed me that on climb out he noticed that the top right section of the rear passenger door was slightly ajar and not flush with the fuselage. I didn't see how this was possible since I had personally locked and checked the door and on taxi out had asked my passenger to re-check the top latch closed, which he confimred. Nevertheless, I attributed the mild buffet with the door not being 'true' with the skin of the aircraft. To satisfy myself, I accomplished another engine run-up, took off solo, and flew around the pattern at an exagerated airspeed and power settings. The craft handled smoothly, indications were good, and 'she purred like a kitten.' feeling satisfied that the problem was the rear door and that the plane was airworthy, I again filed an IFR flight plan to blm. Yet another magneto check and engine run-up showed nothing amiss, and I departed runway 28 with passenger in tow. 5 seconds before lift off I asked my passenger to re-check the integrity of his door and he said it was fully closed. Takeoff, flap retraction, and initial climb out were normal. At approximately 700 ft AGL I commenced a left bank to the east. After about 90 degrees of turn the aircraft began to exhibit a more pronounced vibration than it had on the first leg. The fuel boost pump was still on and I switched tanks, to no avail. I decreased my angle of bank and maintained 700 ft AGL, all the while heading back to idi. I announced my intentions on CTAF and landed on runway 10. An a and P mechanic on the field at the time looked at the engine and initially told me the plane had a partially blocked fuel injector. Upon further inspection the next day, jun xx, he also informed me that the #2 cylinder had a compression of 15/80, 80/80 being normal. I'm not a mechanic but I couldn't understand, and still don't, why the airplane behaved flawlessly when I flew it by myself. Why didn't it display some problem when I was in the pattern? With the advantage of hindsight and my feet planted firmly on the ground, I still don't think I would have done anything differently. Most pilots, after having a 'problem,' say they should have done this or done that, never again, etc. Such is not the case with me. I'm an experienced 11000 hour ATP, with 30 yrs of flying experience. With the facts I had at my fingertips, I believe I would have made the same decision. Thankfully, things did turn out well and we did rent a car and drive to our destination. Did some other pilot or pilots note a 'glitch' or a 'funny sound' and not bother to write it up, or did a mechanic on an oil change observe something but figured it could wait for the upcoming annual? Did this blocked fuel injector and poor compression happen all at once, or was it so insidious and benign so as not to be worth mentioning? This incident demonstrates that even a scrupulous, exacting pilot who tries to cover all bases and stay ahead of the airplane and developing situation can still get burned, almost. Callback conversation with reporter revealed the following: first takeoff reporter experienced mild buffeting, which was attributed to the rear passenger door being slightly ajar. All other instruments and indications were normal. After insuring the rear door was secured, test run and solo check out in the pattern, reporter landed, picked up passenger and again departed. This time after takeoff and in a left bank aircraft exhibited a more pronounced vibration that it had before, so again reporter returned to land. Mechanic and reporter did an engine run-up with no abnormal indications. Later mechanic found partially blocked fuel injector and low compression in the #2 cylinder. Reporter had no further feedback on the engine.

Google
 

Original NASA ASRS Text

Title: ACFT EQUIP PROB. ROUGH RUNNING ENG.

Narrative: ON JUN/SUN/95, I FILED ON IFR FLT PLAN FROM IDI (INDIANA COUNTY/JIMMY STEWART ARPT) IN PA TO BLM, ALLAIRE ARPT, NJ. WX WAS CAVOK WITH A LIGHT W BREEZE. I DEPARTED RWY 28 AND TURNED E TOWARD TYRONE (TON) VOR. CLBING THROUGH 3000 FT I NOTED A MILD BUFFETING. I CHKED THE FLAPS UP, ENG INSTS, ETC. EVERYTHING APPEARED NORMAL. I ELECTED TO RETURN TO IDI TO CHK THE EXTERIOR OF THE ACFT AND ZOB GAVE ME A HDG BACK TO THE FIELD. AT THE TIME I WAS 3-4 MI E OF IDI. AS I SLOWED AND PULLED THE PWR BACK THE BUFFETING CEASED AND EVERYTHING SEEMED NORMAL. AT THIS JUNCTURE I ALMOST OPTED TO CONTINUE THE FLT TO BLM BUT THOUGHT BETTER OF IT. I TOLD ZOB THAT IDI WAS IN SIGHT AND TO CANCEL MY IFR FLT PLAN, WHICH THEY DID. LNDG AND TAXI IN WAS NORMAL. I ACCOMPLISHED ANOTHER MAGNETO CHK, 'EXERCISED' THE PROP, CHKED AND RE-CHKED THE INSTS, PRESSURES, VACUUM, ETC. ALL INDICATIONS WERE NORMAL. UPON PARKING I ACCOMPLISHED A METICULOUS WALK-AROUND OF THE ACFT. NOTHING UNTOWARD WAS DISCOVERED. I WAS ABOUT TO ADVISE MY PAX THAT I WAS GOING TO CANCEL OUR TRIP HOME WHEN ONE OF THEM INFORMED ME THAT ON CLB OUT HE NOTICED THAT THE TOP R SECTION OF THE REAR PAX DOOR WAS SLIGHTLY AJAR AND NOT FLUSH WITH THE FUSELAGE. I DIDN'T SEE HOW THIS WAS POSSIBLE SINCE I HAD PERSONALLY LOCKED AND CHKED THE DOOR AND ON TAXI OUT HAD ASKED MY PAX TO RE-CHK THE TOP LATCH CLOSED, WHICH HE CONFIMRED. NEVERTHELESS, I ATTRIBUTED THE MILD BUFFET WITH THE DOOR NOT BEING 'TRUE' WITH THE SKIN OF THE ACFT. TO SATISFY MYSELF, I ACCOMPLISHED ANOTHER ENG RUN-UP, TOOK OFF SOLO, AND FLEW AROUND THE PATTERN AT AN EXAGERATED AIRSPD AND PWR SETTINGS. THE CRAFT HANDLED SMOOTHLY, INDICATIONS WERE GOOD, AND 'SHE PURRED LIKE A KITTEN.' FEELING SATISFIED THAT THE PROB WAS THE REAR DOOR AND THAT THE PLANE WAS AIRWORTHY, I AGAIN FILED AN IFR FLT PLAN TO BLM. YET ANOTHER MAGNETO CHK AND ENG RUN-UP SHOWED NOTHING AMISS, AND I DEPARTED RWY 28 WITH PAX IN TOW. 5 SECONDS BEFORE LIFT OFF I ASKED MY PAX TO RE-CHK THE INTEGRITY OF HIS DOOR AND HE SAID IT WAS FULLY CLOSED. TKOF, FLAP RETRACTION, AND INITIAL CLB OUT WERE NORMAL. AT APPROX 700 FT AGL I COMMENCED A L BANK TO THE E. AFTER ABOUT 90 DEGS OF TURN THE ACFT BEGAN TO EXHIBIT A MORE PRONOUNCED VIBRATION THAN IT HAD ON THE FIRST LEG. THE FUEL BOOST PUMP WAS STILL ON AND I SWITCHED TANKS, TO NO AVAIL. I DECREASED MY ANGLE OF BANK AND MAINTAINED 700 FT AGL, ALL THE WHILE HDG BACK TO IDI. I ANNOUNCED MY INTENTIONS ON CTAF AND LANDED ON RWY 10. AN A AND P MECH ON THE FIELD AT THE TIME LOOKED AT THE ENG AND INITIALLY TOLD ME THE PLANE HAD A PARTIALLY BLOCKED FUEL INJECTOR. UPON FURTHER INSPECTION THE NEXT DAY, JUN XX, HE ALSO INFORMED ME THAT THE #2 CYLINDER HAD A COMPRESSION OF 15/80, 80/80 BEING NORMAL. I'M NOT A MECH BUT I COULDN'T UNDERSTAND, AND STILL DON'T, WHY THE AIRPLANE BEHAVED FLAWLESSLY WHEN I FLEW IT BY MYSELF. WHY DIDN'T IT DISPLAY SOME PROB WHEN I WAS IN THE PATTERN? WITH THE ADVANTAGE OF HINDSIGHT AND MY FEET PLANTED FIRMLY ON THE GND, I STILL DON'T THINK I WOULD HAVE DONE ANYTHING DIFFERENTLY. MOST PLTS, AFTER HAVING A 'PROB,' SAY THEY SHOULD HAVE DONE THIS OR DONE THAT, NEVER AGAIN, ETC. SUCH IS NOT THE CASE WITH ME. I'M AN EXPERIENCED 11000 HR ATP, WITH 30 YRS OF FLYING EXPERIENCE. WITH THE FACTS I HAD AT MY FINGERTIPS, I BELIEVE I WOULD HAVE MADE THE SAME DECISION. THANKFULLY, THINGS DID TURN OUT WELL AND WE DID RENT A CAR AND DRIVE TO OUR DEST. DID SOME OTHER PLT OR PLTS NOTE A 'GLITCH' OR A 'FUNNY SOUND' AND NOT BOTHER TO WRITE IT UP, OR DID A MECH ON AN OIL CHANGE OBSERVE SOMETHING BUT FIGURED IT COULD WAIT FOR THE UPCOMING ANNUAL? DID THIS BLOCKED FUEL INJECTOR AND POOR COMPRESSION HAPPEN ALL AT ONCE, OR WAS IT SO INSIDIOUS AND BENIGN SO AS NOT TO BE WORTH MENTIONING? THIS INCIDENT DEMONSTRATES THAT EVEN A SCRUPULOUS, EXACTING PLT WHO TRIES TO COVER ALL BASES AND STAY AHEAD OF THE AIRPLANE AND DEVELOPING SIT CAN STILL GET BURNED, ALMOST. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: FIRST TKOF RPTR EXPERIENCED MILD BUFFETING, WHICH WAS ATTRIBUTED TO THE REAR PAX DOOR BEING SLIGHTLY AJAR. ALL OTHER INSTS AND INDICATIONS WERE NORMAL. AFTER INSURING THE REAR DOOR WAS SECURED, TEST RUN AND SOLO CHK OUT IN THE PATTERN, RPTR LANDED, PICKED UP PAX AND AGAIN DEPARTED. THIS TIME AFTER TKOF AND IN A L BANK ACFT EXHIBITED A MORE PRONOUNCED VIBRATION THAT IT HAD BEFORE, SO AGAIN RPTR RETURNED TO LAND. MECH AND RPTR DID AN ENG RUN-UP WITH NO ABNORMAL INDICATIONS. LATER MECH FOUND PARTIALLY BLOCKED FUEL INJECTOR AND LOW COMPRESSION IN THE #2 CYLINDER. RPTR HAD NO FURTHER FEEDBACK ON THE ENG.

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.