B767 flight crew reported a loud squeal from a flight deck window during climb. Flight crew returned to departure airport and landed safely.
Synopsis
B767 flight crew reported a loud squeal from a flight deck window during climb. Flight crew returned to departure airport and landed safely.
Narrative
During our climb through approximately FL280 to our cleared altitude of FL330; a loud audible squeal coming from the area of the Captain's Left #2 window. The tone was high pitch in nature and became progressively louder as the PSI differential increased above 7.6psi. It became so loud that communication amongst one another was nearly impossible without shouting. Additionally; ATC had trouble understanding us. We stopped our climb at approximately FL310 and descended immediately to FL270. Upon reaching FL270; the squeal went away as the cabin pressure regulator adjusted itself and the PSI dipped below 7.6 for 15-20 seconds. As it repressurized; and the PSI went above 7.6 again; the squeal came back as loud and at the same tone. We continued to descend as ATC would allow; the squeal finally ceased at approximately FL240. We stayed level at FL230 while we contacted dispatch and decided upon a course of action. The Relief Pilot returned at approximately this time and we all decided returning to ZZZ was the best course of action. We did not dump fuel as we were able to burn all of our center tank fuel on the return to ZZZ.We were overweight upon landing by just over 8;000 lbs; and wrote up both the window leak discrepancy and overweight landing. We did not declare an emergency at any time as the pressurization of the aircraft was normal at all times.
Second reporter narrative
I was in the crew rest seat when I felt the aircraft suddenly level off and start to descend. I made contact with the guys on the flight deck and asked them if everything was okay and if I needed to come back up front. He (CA) said yes; due to a loud sound coming from his window. He told me to tell the purser that we were going to be diverting back to ZZZ and that we would brief him momentarily. I made way back up front a found the aircraft flying at FL230. The discussion with dispatch and Maintenance Control was already had and the decision to divert was already made. I helped the CA run checklists and helped coordinate communications. No emergency was declared; and an uneventful landing was made in ZZZ at 8000lbs over at around 400-450 ft/min descent rate.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.