Qn# (b)(4).Additional information received on 27 dec 2022 states, "the error has been detected during preventive maintenance, while checking the helium psi value displayed by the pump (fixed).No alarm has been displayed by the pump.After having replaced the helium re.Assy the pump returned to service correctly." returned for investigation was an ac2 helium regulator assembly (p/n 77-3007-001, s/n (b)(6).The sample was returned in a white cardboard box with protective shipping packaging.Visual inspection of the helium regulator assembly was performed and no abnormality was noted.The helium regulator assembly was installed into a known good lab inventory ac2 for functional testing.The pump powered up normally.The system was able to detect helium pressure and displayed the proper helium status.Pumping was initiated.A source side helium leak test was performed and passed.The pump was left to run for over an hour and the helium tank pressure was dropped by 5 psi, which is an expected outcome after several drain tasks.The helium regulator assembly functioned as intended.A device history record (dhr) review was conducted for the lot number/serial number with no relevant findings.The device passed all manufacturing specifications prior to release.The report complaint of helium tank pressure incorrect was confirmed by the field service representative; however, the returned helium regulator passed visual and functional test specifications.Based on a review of the device history record (dhr), the product met specification upon release.The root cause of the complaint is undetermined.No further action required at this time.This will be monitored for any developing trends.
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