639.21—Determination of cost-effectiveness.
        
        (1) 
         Make a written comparison of the cost of leasing the asset with the cost of purchasing or constructing it; and
    
    
        
        (2) 
         Certify to FTA before entering into the lease or before receiving a capital grant for the asset, whichever is later, that obtaining the asset by lease is more cost-effective than purchase or construction of such asset.
    
    
        
        (b) 
         For purposes of this part, obtaining the asset by lease is more cost-effective than purchase or construction when the lease cost calculated under  § 639.25 of this part is less than the purchase cost calculated under  § 639.23 of this part.
    
    
        
        (c) 
         If a recipient is unable to perform the prescribed cost-effectiveness comparison as described in this subpart, it may ask FTA to approve an alternate form of cost-effectiveness evaluation.