Managing my gross weight.
Shortly after my flight lead departed to meet the tanker for our first scheduled aerial refueling of the evening, I received R LIM OFF, G LIM 7.5, and AOA TONE cautions. I pulled up the Built In Test (BIT) page, which displays the status of aircraft systems. I saw that the Stores Management Set (SMS) indicated "not ready" and my stores page indicated that I had no ordnance or external fuel tanks onboard, even though I was carrying a standard combat loadout, including several Joint Direct Attack Munition (JDAM) and a laser Maverick.
After looking outside and verifying my bombs were still on the wing, I radioed my flight lead on our tactical frequency to update him on what I was experiencing. We elected to forgo any troubleshooting until I was joined up with him on the tanker. Our goal was to ensure that I could still get fuel into my centerline tank, have an accurate reading of my total fuel quantity, and ensure the malfunction I was having was only being caused by the SMS.
After getting our fragged amount of gas and seeing a valid fuel reading, we started going through each of the cautions in the NATOPS pocket checklist (PCL). The R LIM OFF and G LIM 7.5 indicated that the aircraft's roll rate limiting and G imiting would not function normally. The AOA TONE caution indicated that I would have to manually calculate the lateral weight asymmetry of the aircraft. There were the expected indications of the SMS failing and the Super Hornet's mission computers (MCs) not being able to calculate how much the jet weighs. The PCL contained no applicable cockpit procedures, so we decided to cycle power to Mission Computer 2 (MC2) in an effort to recover the SMS. This action did not restore the SMS.
After executing the only reasonable troubleshooting step, we decided to continue the mission. With the ATFLIR no longer inventorying, my NTISR capabilities degraded to using my Mark 1, mod 0 eyeballs and night vision goggles. As expected with an inoperative SMS, I also found that I could not enter air-to-air or air-to-ground master mode.
The next few hours were uneventful. Just before we left our assigned airspace for the final aerial refueling of the night, the master caution went off with CAUT DEGD (degraded ability to display cautions) and NO RATS (reduced authority thrust system, a critical system for CVN recoveries) Cautions present and my radar indicating an overheat condition. On the BIT page, the Signal Data Computer (SDC), which controls and monitors fuel quantity and transfer, now also indicated "not ready." I secured the radar to mitigate the overheat condition and broke out the PCL for my new set of cautions.
In the PCL there is a note for the CAUT DEGD caution that states "LOTs 21-24: Backup TOTAL fuel quantity may be reset to zero following MC1 power cycle." I didn't realize that while I still had a readout for the amount of fuel in each of my fuel tanks, they were only estimated values since a failed SDC inhibits the aircraft's ability to determine the actual fuel quantity in each tank. I followed the steps in the PCL for resetting the SDC. As I was flying a Lot 29 aircraft (not 21-24), I elected to cycle power to MC1.
As soon as I hit the switch, the Engine Fuel Display (EFD) flashed "STANDBY." I popped an EFD DEGD on the BIT Page, and all of my tanks on the fuel page indicated "0." There was an estimated total fuel quantity of a little more than 13,000 lbs., which was close to what I had before the SDC Failure. Since our F/A-18Es are Lot 29, I incorrectly assumed that all the values on my fuel page would remain the same, when in reality the note in the PCL should have clued me in that only the total fuel quantity would still be present after cycling power to MC1. Because the estimated total fuel displayed did not account for the fuel I took onboard, we hacked the clock and used my flight lead's fuel state as my new fuel state with the idea that we would have 1,000 lbs. of slop (the last time we compared fuel states I was 1,000 to 1,500 lbs. higher on fuel).
All fixed-wing aircraft operating from an aircraft carrier have a maximum gross weight at which they can make an arrested landing aboard ship. This is commonly referred to as "max trap." The F/A-18E's max trap is 44,000 lbs., and with our current weapons loadout that equated to a fuel state of approximately 6,000 lbs. Without the jet indicating its approximate gross weight and no accurate indication of how much fuel I had, we were going to have to find a different way to determine when I was at my max trap. We pressed on to the tanker and decided we would take the same amount of fuel, place centerline fuel tanks to stop (inhibiting fuel from entering the tank), and take enough gas to get comfortably back to the ship with time to troubleshoot prior to our scheduled recovery. While en route to the tanker, we contacted the Tactical Command and Control (TAC C2) asset that was airborne in country to relay my jet's condition back to the boat.
DURING OUR JOIN ON THE TANKER, a section from our sister squadron (VFA-213) was finishing up their aerial refueling. We ran our game plan by their flight lead, who happened to be CAG and their XO, to see if they had any suggestions or saw any holes in our plan. They agreed with our course of action, but as they were departing the tanker the wingman's WSO came over the radio and said, "Hey, don't forget you can calculate your gross weight by what your airspeed is when you are trimmed to on-speed (8.1 degrees AOA)." It was a great piece of advice. We regularly use our weight and AOA to calculate our airspeed for an "on-speed" approach, but it had not dawned on me to use the calculation backwards and use my AOA and airspeed to calculate gross weight.
On the transit home my flight lead and I compared AOA flying at the same airspeed to approximate my gross weight compared to his. Once we were in communication with the boat, we passed all the indications I had in the cockpit, the procedures we had executed, and our game plan to use airspeed to confirm gross weight. After configuring for landing and determining that I was just above max trap, I reported to the ship that I was ready to come aboard and commenced my approach.
I told Paddles that I had a no RATS (Reduced Authority Thrust System) caution, meaning the arresting gear setting would have to be adjusted. Aside from not being able to uncage my HUD for the approach, the landing was about as normal as a night trap can be. The final casualty of the night was the aircraft's battery charger, which had failed during the flight. This resulted in a dead battery after I had shut down both engines. As a result, I was unable to electrically open the canopy. A special thanks to my Plane Captain, ADAN Ortegasilva, for manually cranking it open so I could make it to midrats in time.
While I was unable to contribute to the NTISR mission that evening, we were able to pull some great lessons learned out of the events. First, emergencies and system failures don't always present themselves in nice, neat cautions that tell you exactly what is wrong with your aircraft. Maintenance eventually traced the cause of the SMS, SDC, and battery-charger failures to a malfunction with the right generator, of which there had been no in-cockpit indications. With seemingly unrelated cautions manifesting for no apparent reason, our ability to troubleshoot was seriously hampered by a problem that was well beyond normal NATOPS systems knowledge. We had to deal with the symptoms of each new caution without knowing the root cause until a significant maintenance investigation located the cause.
Never assume that the person on the other end of the radio knows all of your emergencies unless you've told them. At some point between the TAC C2 that we relayed my situation to in country and the LSOs on the platform, the information about all of my system failures got lost.
Finally, CRM doesn't just include the crew of your own cockpit or section. It can include all the entities involved in the communication chain working to get you back aboard. We underscored the value of great air-wing-level CRM when the -2 WSO of a different squadron was able to add an "Oh, by the way" that become a crucial tool in managing my gross weight for a safe recovery.
BY LT JUSTIN CHALKLEY
LT CHALKLEY FLIES WITH VFA-31
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|Date:||Jan 1, 2015|
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