I bought my sister a pear tree 5 years ago. It blossoms every year then leaf curls and fruit buds go black. She has never had a pear.
Blackening of pear foliage occurs when any kind of physical damage is done. This includes frost or wind damage. More likely, this is pear scab disease and this needs to be sprayed against with fungicide suitable for apple scab which is similar. Spraying needs to start as soon as leaves are produced in spring. The active ingredient myclobutanil is effective.