A vans rv pilot reported that he detected what he thought was a failed engine cylinder and diverted ...

Narrative:

Cruising at 6;500 feet experienced a sudden onset of engine roughness and corresponding reduction of power. Egt of number 4 cylinder was negligible. Not knowing the seriousness of the problem; I began evaluating off field landing sights as I trimmed for best glide speed in anticipation of a full engine out situation. I had the sectional in my lap and saw a paved airport nearby; did some mental estimates on speed; rate of descent and concluded it was makeable. I turned towards the airport; selected the CTAF and requested and received active runway so I could plan the direct approach.next I tried combinations of throttle; RPM and mixture with no success in smoothing out the vibrations. Still able to maintain some power; my attention turned to informing the traffic on CTAF (there's an active flight school there and the pattern was quite busy) that I was inbound with one cylinder out and would be making an expedited landing.through all this; aviate/navigate/communicate; I did not feel; since the engine had been producing some power; that this constituted an emergency; but I was very anxious that one could develop rapidly depending on whatever was wrong. I elected not to squawk 7700; nor did I feel I wanted to divert attention to changing frequency to approach and go through the story. I was focused on getting on the ground as soon as possible.with the runway aligned perpendicular to my flight path and blocked by trees; I spend a lot of time trying to find it. During one glance at the GPS (garmin 430) I noticed I was probably right on the boundary of the delta airspace and had descended to 2;000 feet; but moving away from it. I had observed no other aircraft in my vicinity.the landing was uneventful; and subsequent inspection discovered a completely severed exhaust pipe on number 4.the workload and the anxiety of losing complete power contributed to a possible brief violation of delta airspace without contacting ATC.

Original NASA ASRS Text

Title: A VANS RV pilot reported that he detected what he thought was a failed engine cylinder and diverted to a nearby airport. On the ground; he determined the Number 4 cylinder exhaust pipe had severed completely.

Narrative: Cruising at 6;500 feet experienced a sudden onset of engine roughness and corresponding reduction of power. EGT of Number 4 cylinder was negligible. Not knowing the seriousness of the problem; I began evaluating off field landing sights as I trimmed for best glide speed in anticipation of a full engine out situation. I had the sectional in my lap and saw a paved airport nearby; did some mental estimates on speed; rate of descent and concluded it was makeable. I turned towards the airport; selected the CTAF and requested and received active runway so I could plan the direct approach.Next I tried combinations of throttle; RPM and mixture with no success in smoothing out the vibrations. Still able to maintain some power; my attention turned to informing the traffic on CTAF (there's an active flight school there and the pattern was quite busy) that I was inbound with one cylinder out and would be making an expedited landing.Through all this; aviate/navigate/communicate; I did not feel; since the engine had been producing some power; that this constituted an emergency; but I was very anxious that one could develop rapidly depending on whatever was wrong. I elected not to squawk 7700; nor did I feel I wanted to divert attention to changing frequency to Approach and go through the story. I was focused on getting on the ground ASAP.With the runway aligned perpendicular to my flight path and blocked by trees; I spend a lot of time trying to find it. During one glance at the GPS (Garmin 430) I noticed I was probably right on the boundary of the Delta airspace and had descended to 2;000 feet; but moving away from it. I had observed no other aircraft in my vicinity.The landing was uneventful; and subsequent inspection discovered a completely severed exhaust pipe on Number 4.The workload and the anxiety of losing complete power contributed to a possible brief violation of Delta Airspace without contacting ATC.

Data retrieved from NASA's ASRS site 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	1427751
Time
Date	201702
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Vans Aircraft Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Visual Approach
Flight Plan	None
Component
Aircraft Component	Exhaust Pipe
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Private
Experience	Flight Crew Last 90 Days 6 Flight Crew Total 1272 Flight Crew Type 1272
Events
Anomaly	Aircraft Equipment Problem Less Severe Airspace Violation All Types

A vans rv pilot reported that he detected what he thought was a failed engine cylinder and diverted to a nearby airport. On the ground; he determined the number 4 cylinder exhaust pipe had severed completely.