If the situation is as you describe it is most likely that the plate was cracted before he got to the piano and the very little stresses (1/1000 of a tuning stress) caused the plate to seperate. Plates are designed with a likely 25% safety factor above the usual 40,000 pounds of strain placed upon the plate when tuned at A=440. If a plate breaks with far less strain then the plate is faulty. No other conclusion is even remotedly possible. Newton J. Hunt Piano Tuner=Technician RPT for 32 years nhunt@jagat.com
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