On January 28, 2013, the National Transportation Safety Board was notified that a Beech King Air C90, N14CP, while on contract from Dynamic Aviation to the Bureau of Land Management (BLM), sustained substantial damage to the left wing at an undetermined time and location. BLM was operating the airplane under an exclusive contract as a public aircraft between April 2, 2012, and October 21, 2012. During a post contract inspection on January 21, 2013, substantial damage to the left wing was discovered. There were no reported injuries during this time frame. The accident airplane was on an exclusive use contract to be primarily used in BLM fire management activities in the low-level lead airplane and air attack missions. BLM provided the pilots and crew. Dynamic Aviation provided the airplane and maintenance personnel. During the term of the contract, the airplane had been operated for a total of 318 hours, which consisted of 113 flights; 110 flights were flown by the BLM pilot, and 3 flights, which totaled 5.2 hours, were flown by the relief BLM pilot. About May 10, 2012, government pilots and the contract mechanic first observed deformation/wrinkles to the left wing outboard of the nacelle. The mechanic inspected the area, and after consultation with company supervisors, it was decided to monitor the area for further damage. No entries were made in the maintenance logbooks. On August 15, 2012, the BLM pilot reported to a relief mechanic that he had encountered moderate turbulence and requested the mechanic perform a "turbulent air inspection." The mechanic reported to the pilot that he had completed the turbulent air inspection and found nothing. The BLM pilot stated that when the primary mechanic returned, he stated that the wrinkle appeared to be a little worse. No further action was taken, and the airplane continued to fly under the contract until October 31, 2012. A review of the airplane records showed no entries by either of the pilots or maintenance personnel regarding the noted damage to the left wing. On November 9, 2012, the airplane was flown from Boise, Idaho, to Redmond, California, and returned to the control of Dynamic Aviation. On December 10, 2012, maintenance personnel discovered the damage to the left wing and observed that it had progressed since previous observations. The Hawker Beechcraft repair design office was sent photographs and a description of the damage to have an assessment completed. The assessment revealed that "the damage was consistent with conditions known to exist when the wing assembly has experienced loading in excess of normal operating limits." It was determined that the left outer wing assembly would need to be replaced with a new or serviceable assembly. The Department of the Interior Office of Aviation Services conducted a mishap investigation and submitted a report of the findings on May 17, 2013; a copy of the report is included in the accident docket. As a result of the investigation of this accident, it was determined that the contractor did possess the required FAR 135 certificate, and the contracted airplane was properly certificated for the contract. However, the contracted airplane was neither on the contractors FAR 135 certificate, nor was it required to be under the contract. The Department of the Interior will require that contracted aircraft to be on the contractor's FAR 135 certificate and/or in the Operations Specifications as appropriate. Also, the Department of the Interior now requires load monitoring equipment on various aircraft to monitor the dynamic loads during low-level flight operations.