B747-400 flight crew reported multiple aircraft status messages during different phases of flight. Crew diverted.
Synopsis
B747-400 flight crew reported multiple aircraft status messages during different phases of flight. Crew diverted.
Narrative
FIRE MAIN DECK AFT WARNING EVENTS (Aircraft X) ZZZZ-ZZZZ1. ZZZZ and ZZZZ1This document contains the formal narrative of the events involving multiple FIRE MAIN DECK AFT warnings; two return diversions; a return to stand; maintenance actions; MEL use; fuel spill leak observations; and crew fatigue concerns.1. Aircraft: B7472. Cargo: Approximately 100T strawberries3. Locations: ZZZZ; ZZZZ15. Key Times (UTC): - Wakeup call received XA:55 UTC - Report for Duty XC:24 UTC - First return to ZZZZ shut down: XH:57 UTC - Second attempt OUT/IN: XM:40 / XN:24 UTC - Third departure (with updated MEL): XR:34 UTC - Diversion to ZZZZ1 landing: XU:25 UTC - Arrival Crew Hotel XX:20 UTC - Total Duty time 20hrs 56min.A recurring MID CARGO AFT LOOP A status message was present prior to boarding. Maintenance repeatedly cleared it via CB (Circuit Breaker) pull/reset of main deck cargo smoke detection zones. After takeoff from ZZZZ; approximately four minutes after liftoff; a FIRE MAIN DECK AFT master warning occurred. ATC advised; overweight landing completed safely on RWY XXL ZZZZ. No smoke or fumes observed; only strawberry odor.A second attempt to depart resulted in a return to stand C1. After ENG Start status messages Pack 1; Mid Cargo Loop A; EE CLNG (Electronic Engine Control Cooling) Bypass V; EE CLNG Supply V. After previous sector Fire Warning Mechanics elected to do a Fire System Test which subsequently Failed. During pushback ground crew advised of a fuel leak from RH (Right Hand) wing. Leak continued after pushback onto taxiway 1. Aircraft then returned to stand. ATC made several calls requesting reason then advised aircraft would not be permitted to fly in airspace until confirmation is received.On the third departure; operating under addition of MEL M26-14-01-XXXX; FIRE MAIN DECK AFT occurred in Cruise at FL 320. CA and I were taking crew rest in the bunks for around 80 minutes and heard PA from FO that we were diverting. Exited bunk in darkness to find crew dealing with multiple FIRE MAIN DECK AFT warnings that continued during descent and approach into ZZZZ1. NNC (Non-normal checklist) was carried out with communication challenges. All Crew donned oxygen masks. Radio support was given from 3rd seat by Captain that assisted crew. An unstable approach resulted in a go-around; followed by a successful overweight landing on RWY XX ZZZZ1. Post-shutdown; the master warning sounded several more times on the ground after all checklists had been completed.Both CA and I after landing entered the main deck and verified that there was no smoke or fire. Fire chief came on board asked if could assist and was told no requirement; false warning; however he elected to keep his vehicles and crew close to aircraft for another 10 minutes. Ground staff requested to see a copy of Noise Certificate; and this was complied with.CREW FATIGUE:Crew members had been awake up to 17 hours with no horizontal rest; experiencing two airborne emergency events and one return to stand in the same duty period. Duty Manager call-backs were repeatedly promised but did not occur. No crew replacement was offered despite multiple emergency/abnormal events. Opportunity to obtain horizontal rest only for a very short period (less than 80 minutes for myself and CA whilst other crew were not able).Ops Spec is not applicable to our Part 121 operation and only applies to part 117. B747 fleet is not required to have a FRMS (Fatigue Risk Management System).RECOMMENDATIONS:- Review cargo smoke detection system reliability and eliminate reliance on repeated CB resets when carrying strawberries.- Formalize post-fuel-jettison inspection/venting procedures.- Improve paperwork approval workflow.- Implement policy to stand down replace crew after emergency events.- Reinforce communication discipline under oxygen mask operations. Include evidence-based events in recurrent simulator and training. Review Class E compartments (B747-400) andtheir limitations.- Remind crew especially those traveling on the main deck such as Load Masters and Mechanics that in accordance with the aircraft limitations; under no circumstances is anyone allowed to open the door to explore main deck for possible smoke or flames whilst aircraft is in the air. According to FAA Advisory Circular AC 20-42D our aircraft do not have the required equipment to enter the main deck to fight a fire whilst airborne.- Reference FAA AC No:20-42D Date: 01/14/11 Any compartment over 200 Cubic Feet page 20 section 5-part d / (2) Restrict personnel from entering the cargo compartment for the duration of the flight.When to Use Portable Protective Breathing Equipment (PBE) Portable PBE should be worn before entering the cargo compartment and attempting to extinguish a fire; as outlined in 14 CFR 25.1439. Note that AFM and / or Crew Operations Manual are required to have the appropriate procedure including a calling out the use of portable PBE and other emergency equipment necessary to fight a fire.This report is submitted to promote safety; highlight system reliability issues; improve fatigue risk management and assist the reports submitted by Captain X and Captain Y as well as complying with mandatory reporting requirements in SMS Manual.Additional Comments and Observations:Following the ZZZZ event; in which the crew returned the aircraft to the ground within twelve minutes of a Master Fire Warning after requesting priority handling; it was expected that the crew would be stood down and replaced. In most organizations this would be standard practice.Concerns increased as duty continued. The next sector required a return to stand due to technical issues; including a ground reported fuel leak on the starboard side with a large visible wet patch. The crew were already fatigued to a level that would normally require an augmented crew for the originally planned two sector duty. During the subsequent sector; the same Main Deck Aft Fire warning occurred again; forcing another diversion. In total; the same four crew members experienced two diversions; two emergency fire procedures; and one return to stand without any intervention; replacement; or discussion from the company regarding welfare or operational risk. Forgotten altogether in the company's communication was the significant stress and elevated workload placed on the crew while managing multiple non normal events in quick succession. This generates stress.This pattern suggests a wider organizational culture that prioritizes continuation of duty despite cumulative fatigue; time zone changes; and reduced rest opportunities where lie flat deadhead options are avoided; travel policy is economy or over 6 hours premium economy often leaving crew tired before duty even begins as it is impossible to obtain any horizontal rest. Communication from Duty Managers is inconsistent; and the repeated question Did you request priority handling?" along with the lack of dissemination of reportable events to the wider pilot group raise further concerns."
Second reporter narrative
Returned to ZZZZ following a main deck fire warning. We had 100T of strawberries loaded when the aircraft was declared AOG. Cargo was offloaded and we were sent to the hotel. We were given another aircraft to complete the charter. Aircraft X arrived at XD:15 local and we were scheduled for an XF:25 local departure. I thought the inbound LM (Line Manager) would load the strawberries while it was cool but he was told he had to clear customs with the inbound crew. Getting through the airport in ZZZZ takes a minimum of 60 minutes; usually longer. We were picked up on time but didn't get to the aircraft until 15 minutes before scheduled departure. The aircraft was still empty as we had our LM with us. The APU was off and no ground air conditioning was available. First of the load arrived 40 minutes later and loading took 2h 20m. We pushed back at XI:45 local after waiting for a tug driver.When we arrived at the aircraft (which was empty with the main deck cargo door closed) the mechanic had pulled CB's (Circuit Breaker) for cargo smoke detect main deck zones 1-8 and 9-16. This was due to a recurring MID CARGO AFT LOOP A status message. The message had appeared prior to our boarding and this procedure had cleared the message. The message returned during loading and it was cleared again using the same procedure. We started 2 engines on the bay and ran all 3 packs for 5 minutes prior to pushback to maximize airflow. The status message returned and the same procedure was followed with the CB's being pulled and the message reset prior to starting the 2 remaining engines. 7 minutes after liftoff we had the CARGO FIRE MAIN DECK warning. The mechanic later surmised this was due to loop B for the same zone sensing smoke with a faulty loop A.We were maintaining runway heading as per ATC instructions and had just leveled at 6000'. Since we had briefed on a fire warning being a possibility I requested priority handling and left the flap at 1 and maintained 250 kt while we were heading away from the airport. Once we turned downwind we retracted the flaps and accelerated to 280 kt while the checklist was completed. ATC vectored us for an ILS Rwy XXL in VMC. The warning disappeared and I had CA Y set me up for the ILS. ATC tried to vector me to intercept the ILS inside the FAF but I requested 5Nm further downwind. We completed the after TO (Takeoff) and APP/LDG checklist and the warning returned on downwind and again turning base. We configured for a F30 landing with a Vref of 165 and AB4; advising ATC that we would stop on the runway and reassess since once on the ground we could investigate the main deck for smoke or fire. At no time did we have any smoke or fumes; just the smell of strawberries.Landing and touchdown were normal at 327.6T. After landing we stopped on the runway and a crew inspection confirmed no smoke or fumes. We elected to taxi back to the original gate; and the highest brake temp reading recorded during or after the event was 4 units.All of the crew including Capt Y (PM); Capt X and FO in the jump seats contributed in monitoring; ensuring all checklists were completed promptly and that nothing was missed.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.