C172 flight crew reported engine power loss on takeoff; resulting in an air turnback.

Narrative:

Me and a flight instructor were planning on taking aircraft X; a cessna 172S; to go practice some commercial maneuvers in the southeast practice boxes I was the PIC for this flight. ZZZ was the departure airport. After start-up; we taxied to the north run-up with no issues. A run-up was completed with no issues or negative signs; and the 'before take-off' checklist was completed and a takeoff briefing was completed. We were cleared for take-off xxl and 'fly straight out'. A short field take-off was performed for this particular take off. Adequate rpms were present and all engine gauges were in the green. The take-off was performed and on the climb out the flaps were raised. At about 700-800 AGL (just about over A16) the rpms dropped about 400RPMs for about 4 seconds and the nose began to pitch down. Adequate rpms returned after about 4 seconds and we kept the climb going. I immediately called 'aircraft X mayday mayday we're getting some engine roughness were going for runway xy' and began turning to the east to make a left downwind for runway xy. ATC did a wonderful job of helping us handle this emergency/clearing traffic off the runway. We were cleared to land runway xy quickly. We landed the aircraft safely and cleared the runway with no further issues. A squawk was written up for the incident and the plane was grounded so that maintenance could investigate.

Original NASA ASRS Text

Title: C172 flight crew reported engine power loss on takeoff; resulting in an air turnback.

Narrative: Me and a Flight Instructor were planning on taking Aircraft X; a Cessna 172S; to go practice some commercial maneuvers in the southeast practice boxes I was the PIC for this flight. ZZZ was the departure airport. After start-up; we taxied to the north run-up with no issues. A run-up was completed with no issues or negative signs; and the 'Before take-off' checklist was completed and a takeoff briefing was completed. We were cleared for take-off XXL and 'fly straight out'. A short field take-off was performed for this particular take off. Adequate RPMs were present and all engine gauges were in the green. the take-off was performed and on the climb out the flaps were raised. at about 700-800 AGL (just about over A16) the RPMs dropped about 400RPMs for about 4 seconds and the nose began to pitch down. Adequate RPMS returned after about 4 seconds and we kept the climb going. I Immediately called 'Aircraft X mayday mayday we're getting some engine roughness were going for Runway XY' and began turning to the east to make a left downwind for Runway XY. ATC did a wonderful job of helping us handle this emergency/clearing traffic off the runway. We were cleared to land Runway XY quickly. We landed the aircraft safely and cleared the runway with no further issues. A squawk was written up for the incident and the plane was grounded so that Maintenance could investigate.

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	1753861
Time
Date	202008
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	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	Initial Climb
Route In Use	None
Flight Plan	None
Component
Aircraft Component	Reciprocating Engine Assembly
Person 1
Function	Single Pilot Pilot Flying
Qualification	Flight Crew Private Flight Crew Instrument
Experience	Flight Crew Total 230 Flight Crew Type 160
Person 2
Function	Instructor Pilot Not Flying
Qualification	Flight Crew Commercial Flight Crew Flight Instructor Flight Crew Instrument
Events
Anomaly	Aircraft Equipment Problem Critical