B737-400
Flight Crew Air Transport Pilot (ATP)
Troubleshooting
Aircraft Equipment Problem Critical
Flight Crew Landed As Precaution; Flight Crew Returned To Departure Airport; General Maintenance Action
Aircraft
Aircraft had a noticeable loud howl on takeoff and initial climbout as remarked by both pilots. [We] watched both vibration indicators and all instruments normal. Climbing out of 10;000 FT and above; howling increased and engine one vibration indicator went steadily up above 4.0 to 5.0 and EGT was rapidly increasing to just below red line of approximately 910C. As pilot not flying; [I] told First Officer to pull number one back. We leveled at FL200 advising Center we might have engine problem. Asked Lead Flight Attendant to check out number one engine and had one of our pilots talk to us about vibration and howling he heard. Contacted Maintenance on Company radio and they contacted Maintenance Control. We advised we had run the QRH and Maintenance Control advised we should return to the departure airport as we were only 60 miles south. [We] returned normally to field. Maintenance called later on and they said engine was being changed out as borescope showed internal blade damages. No birds or other FOD ever encountered prior to this event. No conflicts with any other aircraft or any deviations with ATC other than telling ATC we needed to return to field only as a precautionary.
[Narrative #2 had no additional information.]
A B737-400 engine developed a howling sound during climb accompanied by increased engine vibration and EGT; so the crew completed the QRH and returned to the departure airport where severe engine damage was discovered.