For completeness, here's the NTSB report on maintenance to the Valujet plane prior to the accident.
What you see with Valujet is what you see with so many other plane crashes. People take bits of the story (like "The French President's plane was waiting to cross" and "The spacer was missing") and construct an elaborate conspiracy.
Air disasters are particularly susceptible to this becuase they happen so rarely. When a plane goes down, it's usually due to an unbelievable combination of freak circumstances. So the explanations are hard to swallow for most people.
Yeah, with Valujet, if one of them O2 bottles went off, it was over. But from looking at this and a few other of the valujet incidents (like the one where they reset the WoW circuitbreakers on final, causing the spoilers to deploy and blowing all the tires. In that case, it was determined that the flightcrew's decision to troubleshoot yadda yadda yadda; what's scary is that this was a relatively routine problem), electrical problems were a matter of course.
Anyway, from my ignorant perspective: aircraft maintenance as a whole is pretty good; but some airlines do a better job of maintenance than others, and somehow I suspect it's related to how many, how skilled and how well treated those maintenance folks are. Nobody intentionally does a bad job, but fatigue, inexperience/incompetence, and low morale have a measurable effect on what gets done.
I've flown American Airlines, and I've flown Tower Air, and guess which one I only flew once? I ain't qualified to evaluate the work of a jet doctor, but I certainly can see that when 20% of the sealtbelts of a 747 are installed backwards (and pinned to prevent the problem being corrected), something's up. Then when we cross the Atlantic in August at 20,000 feet (I kid you not -- at the very least they could have turned off the GPS readout in back), I sorta wonder...
1.6.6 Maintenance
On May 9 and 10, 1996, the autopilot on the accident airplane was written up by
flightcrews three times for “porpoising.”52 In the May 9 write-up, the corrective action statement
indicated that a complete checkout of the autopilot system was performed in accordance with the
maintenance manual, and that the system was determined to be “normal” during an operational
check. The first of two write-ups on May 10 indicated that the autopilot was porpoising in cruise
flight at flight level 330. The corrective action recorded for this discrepancy was to remove and
replace the autopilot pitch computer. Later that day, the autopilot was described as “porpoising
at all altitudes.” At that point, the autopilot system was assigned to the minimum equipment list
(MEL),53 and placarded as inoperative.
During the flight from DFW to Atlanta on the morning of the accident, the crew
wrote up the cockpit interphone (the service interphone allowing voice communication between
flight attendants and the pilots) as being inoperative. Before departing from Atlanta, a mechanic
removed and replaced the center pedestal handset. After connecting the new handset, the system
was checked, and it still failed to operate. The inoperative interphone was then assigned to the
MEL. According to ValuJet’s FAA-approved MEL for the DC-9, the following operational
procedure was required for the interphone system: “May be inoperative provided: a) alternate
normal and emergency operations procedures are established and used; and b) the passenger
address system is operative.”
On the day of the accident, the airplane was delayed in departing the gate at
Atlanta for the flight immediately before the accident flight because the right auxiliary hydraulic
pump circuit breaker popped. After examining the pump, cleaning the cannon plug pins, and
reconnecting the cannon plug, a mechanic was able to reset the circuit breaker without any
further difficulty.
During the flight from Atlanta to Miami, the public address (PA) system stopped
functioning. According to passengers on that flight, the flight attendants used a megaphone to
communicate with the passengers while the airplane remained airborne, but discovered during
the taxi to the gate that the PA system was once again operable. A SabreTech mechanic
52 Dynamic pitch changes, either induced by pilot input or the autopilot, resulting in an up and down movement
of the airplane’s nose.
53 The MEL lists items of aircraft equipment that may be deferred when inoperable. The MEL is developed by
each operator of an aircraft and must be equivalent to or more conservative that the master MEL, which is developed
by the manufacturer.
37
responded to the captain’s request to meet the plane when it landed and entered the electrical
equipment bay just aft of the nose wheel well and checked the PA amplifier to see if it was hot.
He reported that it was not hot, and that it was loose in its mount. He therefore secured the
amplifier, and the PA system was once again operable. He said that he did not notice any
unusual smells, noises, or vibrations while working in the equipment bay, and that the captain
had said that no circuit breakers had popped en route to Miami. According to the mechanic, the
pilot entered the corrective action the mechanic had taken into the airplane’s log book, and the
mechanic then signed the entry. The log book was retained on the airplane.
At the time of the accident, there were three open MEL items and one open
configuration deviations list (CDL)54 item being carried for N904VJ. Those items were as
follows:
· Left fuel flow gauge inoperative.
· Cockpit interphone inoperative.
· Autopilot porpoising.
· Flap hinge fairing removed.
Maintenance records indicated that the airplane complied with all applicable
airworthiness directives (ADs). AD 96-07-15, issued on May 15, 1996, called for the inspection
of a wire bundle in the overhead switching panel of the cockpit to detect possible chafing or
damage to the wire bundle that might lead to a fire. Maintenance records indicated that the
inspection had been performed on this airplane on May 20, 1995, after issuance of a McDonnell
Douglas Alert Service Bulletin on April 11, 1995. Maintenance records further indicated that no
damage or chafing was found at that time, and that the protective spiral wrap called for in the
service bulletin and the AD was applied to the bundle.
