Airworthiness Directives; Bombardier, Inc. Airplanes

We are superseding Airworthiness Directive (AD) 2011-07-10 for certain Bombardier, Inc. Model BD-100-1A10 (Challenger 300) airplanes. AD 2011-07-10 required revising the Airworthiness Limitations section of the Instructions for Continued Airworthiness; doing detailed visual inspections; removing discrepant material; cleaning the surfaces of the valves, the plug of the sensing port, and the cabin pressure-sensing port plug; securing the insulation; installing a new safety valve, and replacing certain cabin pressure-sensing port plugs. This new AD retains all requirements of AD 2011-07-10, and requires a detailed visual inspection of both safety valves and the surrounding area for foreign material, room temperature vulcanizing (RTV) silicone, contamination, foam on the bulkhead structure, tape or insulation, and loose material; and corrective actions if necessary. This AD was prompted by reports of in-flight loss of cabin pressurization that was attributed to partial blockage of a safety valve cabin pressure-sensing port in conjunction with a failed safety valve manometric capsule. We are issuing this AD to detect and correct blockage of a safety valve cabin pressure-sensing port, which could result in loss of cabin pressure.