After a pc-12 firm landing; the nose strut compressed upon touch down allowing the propeller blades ...

Narrative:

Normal approach profile to 3500' X 50' asphalt runway. No services. Aircraft aoa guidance utilized on approach; call-outs by sic were 'blue diamond to donut;' which I was happy with. Wind direction called 130 @ 13-19; gusty. Tree line to left side of runway; several small hangars to right side. I added 40 degrees flaps on final and yaw damper was disengaged on short final. Pleased with profile and looked good for touchdown point. Just prior to touchdown power was reduced full; holding off for mains to make contact; sudden drop of aircraft (sic noticed sudden drop of aoa) whereupon mains hit and then hard onto nose. At this point blades struck asphalt (approximately 550' down runway). Finish landing roll; turned aircraft around on runway for taxi back to off-load passengers. It was on post flight inspection that the damage was realized. The landing did not seem unusually hard; and passengers were not aware.I will now have more of an appreciation for possible wind-shear conditions due to gusty winds combined with local ground features. When I observe these conditions in the future I may elect to proceed to an alternate airport with better wind to runway alignment or simply a larger landing surface where ground friction possibilities can be minimized.

Original NASA ASRS Text

Title: After a PC-12 firm landing; the nose strut compressed upon touch down allowing the propeller blades to strike the runway. The aircraft had recently been in maintenance. It was later determined the left angle of attach (AOA) system was miscalibrated by 5 units.

Narrative: Normal approach profile to 3500' X 50' asphalt runway. No services. Aircraft AOA guidance utilized on approach; call-outs by SIC were 'Blue Diamond to Donut;' which I was happy with. Wind direction called 130 @ 13-19; gusty. Tree line to left side of runway; several small hangars to right side. I added 40 degrees flaps on final and yaw damper was disengaged on short final. Pleased with profile and looked good for touchdown point. Just prior to touchdown power was reduced full; holding off for mains to make contact; sudden drop of aircraft (SIC noticed sudden drop of AOA) whereupon mains hit and then hard onto nose. At this point blades struck asphalt (approximately 550' down runway). Finish landing roll; turned aircraft around on runway for taxi back to off-load passengers. It was on post flight inspection that the damage was realized. The landing did not seem unusually hard; and passengers were not aware.I will now have more of an appreciation for possible wind-shear conditions due to gusty winds combined with local ground features. When I observe these conditions in the future I may elect to proceed to an alternate airport with better wind to runway alignment or simply a larger landing surface where ground friction possibilities can be minimized.

Data retrieved from NASA's ASRS site as of April 2012 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	840615
Time
Date	200906
Local Time Of Day	1801-2400
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	PC-12
Operating Under FAR Part	Part 91
Flight Phase	Landing
Route In Use	Visual Approach
Flight Plan	VFR
Component
Aircraft Component	Angle of Attack Vane
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 47 Flight Crew Total 10783 Flight Crew Type 858
Events
Anomaly	Aircraft Equipment Problem Critical Ground Event / Encounter Ground Strike - Aircraft Inflight Event / Encounter Unstabilized Approach

After a pc-12 firm landing; the nose strut compressed upon touch down allowing the propeller blades to strike the runway. The aircraft had recently been in maintenance. It was later determined the left angle of attach (aoa) system was miscalibrated by 5 units.