During altimeter and pitot static system recertification, the technician observed the left pitot tube was incorrect and was actually a right one. Further investigation revealed the p/n was misiden-tified as a left pitot tube (p/n PH502-3) when the drain hole and embossed "top" mark were consistent with a right pitot tube (p/n PH502-5). While performing scheduled static system tests, excessive pitot leak was discovered and isolated to the forward nose area. On pitot tube (p/n AN58121) removal, the riser was found to be cracked approximately 50 percent of its circumference. Replaced the tube with a serviceable unit and the system tested satisfactorily. Due to the pitot tube riser's location-below the nose avionics shelf and ahead of an air conditioner condensing coil-the cracked area would not have been visible during a routine visual inspection.
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