B747-400 flight crew reported smoke and odor in the cockpit on departure climb.
Synopsis
B747-400 flight crew reported smoke and odor in the cockpit on departure climb.
Narrative
After retracting flaps up around 4000 Feet; Capt. asked crew Do you guys smell something burning?"Within 2 seconds; I smelled the strong electrical and plastic burning odor. As soon as Capt. advised ATC; ATC instructed to descend 2000 Feet and HDG 330 for RWY XX APP.Immediately we donned oxygen mask to avoid inhaling fumes or smoke.While I requested PM set up for ILS RWY XX and brief the APP; I briefly saw 'Equip Cooling' EICAS message. I ordered the center seat observer to conduct checklist.As we descend and close to approach; the odor disappeared thus we took off mask to increase the communication. We had a lot of difficulty in communicating due to oxygen mask noise.After Equip cooling message; Autobrakes system became inoperative therefore we conducted manual landing.After landing the mechanic reported that inside of E&E Bay was very hot.Cause: Prior to departure we discussed deferred item "21-XX-XXX and 21-XX-XX"As Trim Air was closed; the sufficient cooling air was not supplied to E/E bay. After the event; the mechanic found that the exhaust fan was overheated and burnt.Besides; we talked about the side tone noise in the radio system in the fleet. With oxygen mask on; the side tone noise made our communication worse through the inter comm.We are barely able to hear ATC and communicate each other.It was quite a challenging factor in urgent situationSuggestions: When we had a debriefing; I found that other crew did not hear my requests because of excessive noise in radio.I could have checked with other crew if they were acknowledged my intentions and requests in poor radio environment."
Second reporter narrative
On departure around 2000 feet I noticed an electrical burning smell. It was a faint odor and I wasn't yet 100 percent sure. About 15 seconds later I definitely was smelling something burning and asked the other crew members if they smelled it. F/O who was PF confirmed he smelled it; F/O in the first observer seat could not smell it. Another 15 seconds and around 4000 feet the electrical burning odor increased dramatically and we all confirmed it. The odor was acidic and electrical burning in nature with light smoke. I advised ATC; stating we had electrical smoke in the cockpit and needed to return to ZZZ. We were given a vector and descent to 2000 feet. I donned the oxygen mask and informed the other crew members to do the same. An EQUIP COOLING EICAS advisory was briefly annunciated then cleared. Communication was extremely difficult with the use of the oxygen masks as the sound of us breathing was overpoweringly loud which made it almost impossible to communicate with each other via the intercom. I mistakenly went to the QRC for an immediate action item for SMOKE IN THE COCKPIT; then decided running the QRH was not the highest priority as we were landing shortly; had already donned the oxygen masks and my attention was needed in communicating with ATC and setting up the aircraft for the approach. The PF used hand signals to aid in communication as we setup the aircraft for the ILS XX and briefed the approach. When ATC initially wanted to turn us inbound on the approach I asked for a delay so we could finish setting up the aircraft. The AUTOBRAKE EICAS Advisory annunciated when we tried to select autobrakes for landing so we briefed manual braking. Once the aircraft was setup and the checklists completed through the Approach checklist; I lifted my mask to check for smoke odors and it as much less. I advised the crew I was removing my mask as the increased ability to communicate clearly was a greater threat then the fumes smell at that time. Once we had our masks off; I confirmed if each of us felt we were prepared for the approach and landing. We all concurred and proceeded to an uneventful landing. Fire trucks met us as we cleared the runway on Taxiway 1 and they advised they saw no thermal heat spots on the aircraft to which I informed them we did not show any high brake temps either. Advised Tower we were stopping on the taxiway to figure out parking location. I asked the F/O in the observer's seat to inform Dispatch of our divert and that we were safe on the ground via ACARS. Once we had parking information we taxied to parking and fire command followed us.Both First Officers did an outstanding job as professional Airmen. PF remained focused on safe control of the aircraft and its state at all times while overcoming difficult communication challenges due to the use of the oxygen masks. The First Observer was proactive in aiding and backing up the PF and PM in their duties while not adding to the workload and compounding the difficult communication issues.Suggestions: The most surprising element of this event for me was how difficult communication was with the oxygen masks. This is something that a lot of pilots go their whole career without ever experiencing and I think it is an understated threat. It would be difficult to replicate in the training environment. The F/O in the observer seat was able to determine; not long after we donned the masks; the use of the hot mic was picking up the noise of our breathing; which was extremely loud and distracting. Turning off the hot mic helped and would be a good item to discuss for recurrent training.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.