The FAA is superseding Airworthiness Directive (AD) 99-23-18, AD 2005-03-07, AD 2013-12-07, and AD 2014-04-07, which applied to certain Bell Helicopter Textron Canada (now Bell Textron Canada Limited) Model 407 helicopters. AD 99-23-18 required revising the life limits for certain parts, replacing each part that had exceeded its life limit, and revising the Airworthiness Limitation Section (ALS) of the existing maintenance manual. AD 2005-03-07 required establishing a maximum accumulated Retirement Index Number (RIN) count for certain crosstube assemblies and revising the ALS of the existing maintenance manual. AD 2013-12-07 required inspecting the tailboom assembly for a crack, loose rivet, or other damage and depending on the inspection results, replacing certain parts. AD 2014-04-07 required preflight checking, repetitively inspecting for a crack in certain tailbooms, modifying and re-identifying certain tailbooms, installing an improved horizontal stabilizer assembly, and revising the ALS of the existing maintenance manual. Since the FAA issued those ADs, a report was received of a crack on the tailboom lower skin due to fatigue damage and new and more restrictive airworthiness limitations have been issued. This AD was prompted by a report of a crack on the tailboom lower skin due to fatigue damage and the issuance of new and more restrictive airworthiness limitations. This AD requires incorporating into existing maintenance records requirements (airworthiness limitations) as specified in the ALS service information. The FAA is issuing this AD to address the unsafe condition on these products.