Da-20 CFI reported low engine RPM during climb and made emergency landing at a nearby airport.

Attributes
ACN	1648148
Time
Date	201905
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	DA20 Undifferentiated
Operating Under FAR Part	Part 91
Flight Phase	Climb
Route In Use	Direct
Flight Plan	None
Person 1
Function	Instructor Pilot Flying
Qualification	Flight Crew Commercial Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 300 Flight Crew Total 701 Flight Crew Type 391
Events
Anomaly	Aircraft Equipment Problem Critical

Narrative:

[In the morning]; me and my student departed. We climbed to 3500' and departed northwest toward ZZZ. After clearing [airspace]; we attempted to climb to 4500' the RPM in climb dropped to 2100RPM. I attempted to put the aircraft in cruise and the RPM dropped to 1000RPM and the throttle cable was stuck in between of the way full and full. I was only able to produce 1000RPM on the engine. At that point I was looking for the best place to land. ZZZ was 6 miles away. With our given altitude and calculation; I realized we could make the runway. I made a call on ZZZ's CTAF to let them know that I would be make an emergency landing on a straight in for runway 35. Once close enough to the runway and landing was assured; I added flaps; initiated a forward slip and landed the aircraft. I taxied off the runway and to the FBO and shutdown.

Original NASA ASRS Text

Title: DA-20 CFI reported low engine RPM during climb and made emergency landing at a nearby airport.

Narrative: [In the morning]; me and my student departed. We climbed to 3500' and departed Northwest toward ZZZ. After clearing [airspace]; we attempted to climb to 4500' the RPM in climb dropped to 2100RPM. I attempted to put the aircraft in cruise and the RPM dropped to 1000RPM and the throttle cable was stuck in between of the way full and full. I was only able to produce 1000RPM on the engine. At that point I was looking for the best place to land. ZZZ was 6 miles away. With our given altitude and calculation; I realized we could make the runway. I made a call on ZZZ's CTAF to let them know that I would be make an emergency landing on a straight in for runway 35. Once close enough to the runway and landing was assured; I added flaps; initiated a forward slip and landed the aircraft. I taxied off the runway and to the FBO and shutdown.

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.