Summary
We propose to adopt a new airworthiness directive (AD) for certain Learjet Inc. Model 45 airplanes. This proposed AD was prompted by reports of non-conforming windshield supports (coupe rails). This proposed AD would require a general visual inspection to detect gouging and scratches and to determine if a radius has been removed; an ultrasound inspection to measure the dimensions of the lower coupe rails; an eddy current inspection to detect cracks of the lower coupe rails; replacement of the lower coupe rails if necessary; and revision of the maintenance or inspection program, as applicable. We are proposing this AD to detect and correct non-conforming windshield supports, which could result in uncontrolled cabin depressurization. Non-conforming windshield supports could also compromise the capability of the windshield to withstand a bird strike.