The pilot of an experimental single engine declared an emergency and diverted to a nearby airport wh...

Attributes
ACN	908153
Time
Date	201009
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Experimental
Operating Under FAR Part	Part 91
Flight Phase	Climb
Route In Use	None
Flight Plan	None
Component
Aircraft Component	Engine
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Private Flight Crew Instrument
Experience	Flight Crew Last 90 Days 8 Flight Crew Total 780 Flight Crew Type 230
Events
Anomaly	Aircraft Equipment Problem Critical Airspace Violation All Types

Narrative:

Climbout was normal but when almost at planned cruise of 10;500 ft the engine coughed and started to run very rough. I immediately turned around and headed via the highway below towards ZZZ; in case a total engine failure occurred. I called ATC and declared an emergency in case I had to land on the highway and needed assistance. There was a tfr off to my left about 1 mile (I am not sure if active; but it showed on my GPS) of about 1 mile diameter close to my path; I assume for a forest fire watch. I came close but don't think I entered the tfr. I had difficulty maintaining level altitude and was worried about losing the engine so I came close to minimize the distance to the airport.I made it over ZZZ with some altitude to spare. The approach and landing were normal with a good touchdown. We tied the airplane down and departed with the local sheriff's department; who responded. The airplane is currently under investigation by an a&P; and it looks like it was a combination of a restricted injector nozzle on 1 cylinder and a magneto failure.

Original NASA ASRS Text

Title: The Pilot of an experimental single engine declared an emergency and diverted to a nearby airport when the engine began to run rough and lose power over mountainous terrain. The pilot and his passenger landed safely.

Narrative: Climbout was normal but when almost at planned cruise of 10;500 FT the engine coughed and started to run very rough. I immediately turned around and headed via the highway below towards ZZZ; in case a total engine failure occurred. I called ATC and declared an emergency in case I had to land on the highway and needed assistance. There was a TFR off to my left about 1 mile (I am not sure if active; but it showed on my GPS) of about 1 mile diameter close to my path; I assume for a forest fire watch. I came close but don't think I entered the TFR. I had difficulty maintaining level altitude and was worried about losing the engine so I came close to minimize the distance to the airport.I made it over ZZZ with some altitude to spare. The approach and landing were normal with a good touchdown. We tied the airplane down and departed with the local Sheriff's department; who responded. The airplane is currently under investigation by an A&P; and it looks like it was a combination of a restricted injector nozzle on 1 cylinder and a magneto failure.

Data retrieved from NASA's ASRS site as of April 2012 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.

The pilot of an experimental single engine declared an emergency and diverted to a nearby airport when the engine began to run rough and lose power over mountainous terrain. The pilot and his passenger landed safely.