Lsa pilot reported a loss of engine performance that led to a diversion and a successful landing.

Attributes
ACN	1495791
Time
Date	201711
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	Light Sport Aircraft
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	None
Flight Plan	None
Component
Aircraft Component	Engine
Person 1
Function	Instructor Pilot Flying
Qualification	Flight Crew Flight Instructor Flight Crew Instrument Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 30 Flight Crew Total 4000 Flight Crew Type 500
Events
Anomaly	Aircraft Equipment Problem Critical

Narrative:

During flight instruction a noticeable engine roughness occurred. The flight was conducted under VFR and utilizing flight following. I immediately turned on carburetor heat to no avail and turned back toward ZZZ (airport of operations) that was about 17 nm distant. By adjusting the throttle; rpm was kept at cruise setting and roughness stopped. After approximate 8 miles of flight the roughness returned and would not subside. I notified the approach controller of the situation and asked for an expedited path to the closest airport. He cleared me direct ZZZ1 and asked [about] souls and fuel on board; with two souls and 3 hours fuel. He then switched me to ZZZ1 tower who cleared me to land. The approach to runway was uneventful with the engine running rough but producing more than adequate power. The landing was uneventful and taxied to the FBO without incident.

Original NASA ASRS Text

Title: LSA pilot reported a loss of engine performance that led to a diversion and a successful landing.

Narrative: During flight instruction a noticeable engine roughness occurred. The flight was conducted under VFR and utilizing Flight Following. I immediately turned on carburetor heat to no avail and turned back toward ZZZ (airport of operations) that was about 17 nm distant. By adjusting the throttle; rpm was kept at cruise setting and roughness stopped. After approximate 8 miles of flight the roughness returned and would not subside. I notified The Approach controller of the situation and asked for an expedited path to the closest airport. He cleared me direct ZZZ1 and asked [about] souls and fuel on board; with two souls and 3 hours fuel. He then switched me to ZZZ1 tower who cleared me to land. The approach to runway was uneventful with the engine running rough but producing more than adequate power. The landing was uneventful and taxied to the FBO without incident.

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.