Prior to accepting an assignment  the expert must inform his client of the rates of his fees. 

Whenever the appraisal or valuation requires special knowledge that the expert  lacks, he will call upon a competent specialist.

If the specialist's fees have not been included in the fees quoted the client must be made aware of this before the appraisal is carried out.  The expert fulfils his task with impartiality, to the best of his abilities and as conscientiously as possible. He cannot be held liable for an appraisal error.