C172 flight instructor reported a loss of engine power during a go-around from a simulated engine fa...

Narrative:

I initiated an engine failure on my student at 4500 feet and had him steep spiral down. Upon reaching 1500 feet AGL he recovered from four rotations and began to configure the aircraft for the simulated engine failure power off landing. Upon reaching 550 feet AGL he initiated a go around adding full power immediately. On climb out a very strong engine vibration began and we lost much of our available power. I turned carb heat back on in the event it was icing but it didn't correct the engine vibration. I then adjusted mixture leaning it out and pulled power to idle then firewalled it at which point power slowly came back. I then diverted to the nearest airport with services and informed operations and had maintenance inspect the aircraft. It was determined that a fouled plug was most likely the cause and after a run up the aircraft was flown back to [home airport]. No further incident occurred.

Original NASA ASRS Text

Title: C172 flight instructor reported a loss of engine power during a go-around from a simulated engine failure maneuver. After diverting; Maintenance concluded that a fouled spark plug was the likely cause.

Narrative: I initiated an engine failure on my student at 4500 feet and had him steep spiral down. Upon reaching 1500 feet AGL he recovered from four rotations and began to configure the aircraft for the simulated engine failure power off landing. Upon reaching 550 feet AGL he initiated a go around adding full power immediately. On climb out a very strong engine vibration began and we lost much of our available power. I turned carb heat back on in the event it was icing but it didn't correct the engine vibration. I then adjusted mixture leaning it out and pulled power to idle then firewalled it at which point power slowly came back. I then diverted to the nearest airport with services and informed operations and had maintenance inspect the aircraft. It was determined that a fouled plug was most likely the cause and after a run up the aircraft was flown back to [home airport]. No further incident occurred.

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	1449264
Time
Date	201705
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	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	Initial Climb
Component
Aircraft Component	Engine
Person 1
Function	Instructor
Qualification	Flight Crew Commercial Flight Crew Flight Instructor
Events
Anomaly	Aircraft Equipment Problem Less Severe

C172 flight instructor reported a loss of engine power during a go-around from a simulated engine failure maneuver. After diverting; maintenance concluded that a fouled spark plug was the likely cause.