Date: 201705
Local time of day: 0601-1200
Location: ZZZ.ARTCC, US
Light: Daylight
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Electrical Power
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Second reporter function: First Officer; Pilot Flying
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Automation Aircraft Other Automation; Person Flight Attendant; Person Flight Crew
Result: Air Traffic Control Separated Traffic; Flight Crew Diverted; Flight Crew Returned To Departure Airport; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Landed As Precaution
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Flight was originating after overnight maintenance for electrical problems including TR1 circuit breaker (CB) and equipment cooling fan circuit breaker being popped in flight. It was a normal preflight and pushback except for a fuel discrepancy due to the previous days out of service for maintenance. After engine start we noted the Equipment Cooling Inop light illuminated and found the normal equipment cooling fan circuit breaker popped. We coordinated with Dispatch and MX for a deferral off the gate then taxied for takeoff.After a normal departure climbing through approximately 15;000 ft the Equipment Cooling Fan Inop light illuminated again. We verified the switch in ALT per the QRH and the circuit breaker for the ALT fan was still in. I did a more comprehensive review of the previous day's write-ups and realized we might be following the same failure chain as the day before. We discussed alternates; coordinated with the F/A's (Flight Attendants) concerning the previous fumes write-up; and got Dispatch on the radio to advise of our concerns. We had to radio because ACARS was also intermittent at that time. We were level at cruise when [a Flight Attendant] called to advise us there was an odor of hot electrical equipment in the aft galley and mid cabin but it was faint. We began to review the Smoke/Fumes Checklist. A few minutes later she called again and said the odor was now stronger; no visible smoke; and she was feeling a bit nauseated and light headed. I told the F/A's to secure the cabin for a [diversion]; we donned our masked in the cockpit; and I asked the F/O (First Officer) to [advise ATC] and begin the divert to [an airport] approximately 70 miles on our nose and VFR. As he began the descent I realized my mask MIC was intermittent at best so I told him to fly and talk while I ran the checklists and set us up for an approach. My mask worked to coordinate some checklist items with the F/A's and occasionally to coordinate with the F/O but mostly we were pointing and acknowledging with thumbs up or I was pulling my mask away to speak to him.  As I completed the Fumes Checklist we got a Pressurization Auto Fail light and shortly thereafter a Cabin ALT Warning horn. I switched from programming for the arrival to the QRC for Cabin ALT Warning horn. The cabin altitude was about 10;500 ft climbing slowly. I ran the checklist and with the outflow valve closed the cabin altitude immediately began a rapid descent. I went back to setting us up for approach. On downwind the left generator dropped off the bus and the F/O noticed it and asked if he should start the APU and put it on the bus. I affirmed that decision and he did so. At that point with landing numbers from the FMC; turning base to a long runway VFR I took the aircraft from the F/O and asked him to check my cockpit setup for approach. We noticed the cabin was over-pressurizing with about a 7psi differential and the aircraft at 8000 ft MSL so I directed the F/O to fully open the outflow valve and go to full cold on the packs. ATC asked us if we could slow for sequence and we said no we wanted to get on deck as soon as possible so they cleared the final and we continued in. At about 14 miles on the Localizer the A autopilot failed so I began hand flying the DECEL and we began to configure. The field was in sight. At about five miles and approximately 3000 ft MSL and glideslope intercept; I lost all my primary flight instruments except altitude and my LOC/GS indicators. I looked over and realized my F/O still had instruments and passed control to him for the landing and continued to configure.Completing the Landing Checklist we noted no green light on the flaps and antiskid inop. I decided based on the runway length and condition to continue after a quick visual check of the slats on both sides and advised the F/O to rollout with reverse and be easy on the brakes. On landing we had normal spoiler deployment but only the right reverser showed deployed despite both handles being up. I called the malfunction and the F/O adjusted reverse and maintained centerline for the rollout. After landing we cleared the runway and stopped. I decided to unmask so we could communicate and had to use the PA to get the F/A's to come up on the interphone because the F/A Call was not working. I confirmed with them that there was no smoke in the cabin and they were ok with a taxi to a gate. I then made a PA to the Passengers that we had experienced an electrical malfunction requiring a diversion for safety. I asked for their patience and told them we would taxi to a gate and begin accommodating their continued travel as soon as possible. We taxied to the gate and shut down. After the Shutdown Checklist I went to the back; checked on the F/A's; and again made a PA thanking the Passengers for their patience and cooperation in re-accommodating them.


Second narrative: After pushing from [the gate] and placing the electrical busses to the Eng Generators; the Electrical Cooling OFF Light illuminated. We discovered the Elec Normal Blower circuit breaker was popped. The Captain called Maintenance and completed MEL Procedures for this issue. He noted that this was a repeat issue/write-up for this aircraft from the previous day. We continued on ALT Electrical Cooling in accordance with Maintenance guidance; and proceeded to Runway 1R for takeoff. On the climb out passing approximately 15;000 ft; the Electrical Cooling OFF light came on again in ALT Mode. We reviewed the QRH procedure; confirmed the Elec ALT Blower circuit breaker was in; and continued the climb to 33;000 ft. The Captain reviewed the logbook in depth and saw that the aircraft had experienced issues with Equip Cooling; Fumes in the Cabin; and TR1 failure. The Captain took time to brief the Flight Attendants of the previous issues and to be prepared if similar issues arise; as well as how to inform us if they notice odors; fumes; or smoke. We also discussed our contingencies for diverts at certain points of the flight in case needed. Soon after we were cleared to and climbed to FL 340; the F/As called to say they were smelling an odor; and one F/A was feeling light headed. The Captain made the decision to divert. He passed PF (Pilot Flying) duties to me and I informed ATC and that we required a divert. We donned our Oxygen masks and began an immediate descent to 15;000 ft per ATC instructions and turned direct to [the diversion airport]. The Captain's intercom only worked intermittently; creating a more difficult communication problem than is normal for being on the O2 Masks. I took the ATC COMMS for the remainder of the flight. The Captain began working the Smoke/Fumes Checklist and was coordinating with the F/As. We got an Auto Fail light on the Pressure Control Panel followed by a Cabin Warning horn and light; so the Captain switched to the Cabin Pressure Warning Checklist. He closed the Outflow Valve to preserve Cabin Pressure; and we continued the descent to below 10;000 ft. The Captain set up the cockpit for landing. Descending past approximately 12;000 ft; multiple caution lights came on and I saw that ENG GEN 1 was off line. I asked the Captain if he wanted me to start the APU and put Electric 1 on the APU Bus as a precaution; and he agreed to do that. After the APU was ready; I selected the APU Bus for Electric 1. None of the Electric 1 services seemed to return. As we descended through 8000 ft and on downwind; the Captain noticed the Cabin Pressure was high for our altitude so he used the Manual Valve Control to adjust the pressure. He took PF duties and directed me to review the approach set up for landing; and to begin depressurizing and cooling the aircraft for landing since we were still in Manual on the Pressure Control Panel. We received vectors and clearance to final approach; and got established on final at approximately 25 miles. ATC asked if we could slow for the arrival yet; and we responded that we needed to keep our speed fast as long as feasible. ATC approved; so we remained at 250 knots until 12-15 miles and began to slow. At around 20 miles on final; the A Autopilot disconnected and the Captain continued the approach flying manually. At 12 miles; we began configuring for landing by selecting flaps 5. While approaching glideslope intercept; the Captain's instrumentation began to fail; including the HGS; ADI; and other Navigation instruments. He saw that my instrumentation was still operating; so he passed PF duties to me and instructed me to land. We continued to configure for landing; received landing clearance and landed. On rollout while I began to select Thrust Reverse on both engines; the Captain called out that the left Reverser light was not illuminated. As I neared TR (Thrust Reverser) Detent 2 I felt a slight swerve in the aircraft and deselected the Reverse to Detent 1 and decelerated using wheel brakes. After clearing the Runway; we confirmed with the F/As if there was a need to deplane in position on the taxiway; and with their concurrence we continued to [the gate].

Second callback: The reporter stated when reviewing the log book prior to flight they realized there was a lot of maintenance done on the aircraft associated with the electrical system. The reporter stated the equipment cooling fan was deferred and was operated using the alternate system; (the equipment cooling light came on again in flight and the circuit breaker was not popped). The reporter stated along with the cooling fan issue they received a report from the flight attendants of a burning smell in the cabin. The reporter stated they lost the left generator bus; so they started the APU to use the generator to power the left bus but the APU generator would not come on line to power the bus. The reported stated they donned the O2 masks when TR1 failed causing the overhead panel to light up like a Christmas tree; at the same time the cabin started losing pressurization; at which time the Primary Flight Instruments on the Captain's side were lost. The reporter stated the TR1 was isolated and could not be powered from another source. The reporter also stated when going through the QRH check list for one item another fault would occur which created a very busy cockpit. The reporter stated it's difficult to remember the sequence of events; but it was possible the same sequence of events occurred the day before which was the reason for the maintenance. The reporter stated at this time they do not know the primary cause of all the failures.

Synopsis: B737 flight crew reported a cascading electrical failure and fumes in the cabin.