Section 151.91 - Removal of obstructions(a) The removal or relocation, or both, of obstructions, as defined in Technical Standard Order N18 is eligible under the Program in cases where definite arrangements are made to prevent the obstruction from being recreated. In a case where removal is not feasible, the cost of marking or lighting it is eligible. The removal and relocation of structures necessary for essential airport development is eligible. The removal of structures that are not obstructions under § 77.23 of this chapter as applied to § 77.27 of this chapter are eligible when they are located within a runway clear zone.(b) The removal and relocation of an airport hangar that is an airport hazard (as described in § 151.39(b) ) is eligible, if the reerected hangar will be substantially identical to the disassembled one.(c) Whenever a hangar must be relocated (either for clearance of the site for other airport development or to remove a hazard) and the existing structure is to be relocated with or without disassembly, the cost of the relocation is an eligible item of project costs, including costs incidental to the relocation such as necessary footings and floors. However, if the existing structure is to be demolished and a new hangar is to be built, only the cost of demolishing the existing hangar is an eligible item.Doc. No. 1329, 27 FR 12357, Dec. 13, 1962, as amended by Amdt. 151-22, 33 FR 8267, June 4, 1968