Ignition Override,
I’ve flown the -10, -50 and currently fly the -80. Your source is correct on the brake system on those planes. I don’t have my manuals anymore for the -50 but I never remember moving the lever out of the both position but we didn’t single engine taxi either (the old days of cheap fuel.)
Yes you can dispatch with a thrust reverser inop but the hydraulic accumulator circuit breaker is pulled and collared. (I’m at home and don’t have access to a MEL) If I remember correctly that circuit breaker is behind the Captains left shoulder. Not an easy maneuver in the heat of battle when you’ve lost all your brakes. To expect the Captain to loosen his straps, spin around in his seat, find the circuit breaker in a sea of C/Bs, yank off the collar, push back in the circuit breaker, spin back around in his seat and then deploy the marginally effective thrust reverser. Even at full reverse the thrust reversers on the -50 are more of a noisemaker than anything else. They are more effective at high speeds (not much) then low speeds.
This accident bothers me because the DC-9 brake system is very straightforward with two completely independent systems. At my carrier we had a string of transfer pumps crack on several aircraft leading to a complete loss of hydraulic quantity on each system. We have replaced all the transfer pumps with a more “robust” pump. Since then we have not had any more problems.
Even if NWA had a cracked transfer pump the crew would have lost steering that would force them to set the brakes and call for a tug. If it is not a cracked transfer pump then crew should have had at least one brake system powered by one of four pumps delivering 3000 psi hydraulic pressure. With a dual flame out and no APU they should have had two accumulators good for 5 brake applications before depleting the accumulators.
I understand the Captain is in serious condition with head wounds and fuel burns, while the first officer was also hurt, but not as badly. On the ground, one mechanic apparently received chemical burns, and a ramp agent who ran over to assist was overcome with jet fuel that sprayed into his eyes.