(a) Except as provided in paragraph (b) of this section, it is filed in writing within 2 years after accrual. For purposes of this part, a claim accrues at the time of the accident or incident causing the loss or damage, or at such time as the loss or damage should have been discovered by the claimant by the exercise of due diligence.

(b) It cannot be filed within the time limits of paragraph (a) of this section, because it accrues in time of war or in time of armed conflict in which any armed force of the United States is engaged or if such a war or armed conflict intervenes within 2 years after it accrues, and if good cause is shown, and if it is filed not later than 2 years after that cause ceases to exist, or 2 years after the war or armed conflict is terminated, whichever is earlier.