Airworthiness Directives; Jetstream Aircraft Limited HP137 Mk1, Jetstream Series 200, and Jetstream Models 3101 and 3201 Airplanes

This amendment supersedes Airworthiness Directive (AD) 87-07- 01, which currently requires the following on Jetstream Aircraft Limited (JAL) HP137 Mk1, Jetstream series 200, and Jetstream Model 3101 airplanes: repetitively inspecting the nose landing gear (NLG) top cap assembly securing bolts for looseness or cracks, retorquing any loose security bolt, and replacing any cracked security bolt. AD 87-07-01 also provides the option of incorporating an NLG modification as terminating action for the repetitive inspections. A report of cracked and loose bolts found on an airplane with the above-referenced NLG modification prompted this action. This action: retains the repetitive inspections required by AD 87-07-01; increases the AD applicability to include Jetstream Model 3201 airplanes and airplanes that have the NLG top cap assembly modified in accordance with AD 87-07-01; requires replacing two of the NLG top cap assembly securing bolts; and incorporates a new NLG top cap assembly that would eliminate the repetitive inspection requirement of the AD. The actions specified in this AD are intended to prevent failure of the NLG caused by cracked or loose securing bolts, which, if not detected and corrected, could lead to NLG collapse and damage to the airplane.