GA pilot reported an off field landing after the propeller spinner and backing plate failed in fligh...

Attributes
ACN	1493470
Time
Date	201710
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	Small Aircraft High Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	None
Component
Aircraft Component	Propeller Spinner
Person 1
Function	Single Pilot
Qualification	Flight Crew Private
Experience	Flight Crew Last 90 Days 11 Flight Crew Total 776 Flight Crew Type 584
Events
Anomaly	Aircraft Equipment Problem Critical

Narrative:

I was level at 3000 ft in cruise configuration when an enormous vibration started. I closed the throttle to minimize the vibration and [advised ATC]. Even at idle; the vibration was so bad that I worried that the engine was going to be ripped off of the airframe. I didn't know the cause of the vibration. I supposed that something in the engine had failed. ATC was helping me find a private grass strip. But I never did see [it] and ended up selecting a soybean field. Once I was sure I had the field made; I switched the mags off. The prop came to a stop and I could see the damage to the tip of the prop. The landing was smooth with no damage to the airplane or anything on the ground. After I got out of the airplane; I could see that the spinner and its mounting bracket had been ripped off also (the mounting lugs of the bracket were still under the prop bolts).

Original NASA ASRS Text

Title: GA pilot reported an off field landing after the propeller spinner and backing plate failed in flight.

Narrative: I was level at 3000 ft in cruise configuration when an enormous vibration started. I closed the throttle to minimize the vibration and [advised ATC]. Even at idle; the vibration was so bad that I worried that the engine was going to be ripped off of the airframe. I didn't know the cause of the vibration. I supposed that something in the engine had failed. ATC was helping me find a private grass strip. But I never did see [it] and ended up selecting a soybean field. Once I was sure I had the field made; I switched the mags off. The prop came to a stop and I could see the damage to the tip of the prop. The landing was smooth with no damage to the airplane or anything on the ground. After I got out of the airplane; I could see that the spinner and its mounting bracket had been ripped off also (the mounting lugs of the bracket were still under the prop bolts).

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.