?? JT8D Starter Valve again ??
Seems that several customers once didn't have any START VALVE OPEN annunciator on TBC product [starter cut-out verified manually (by a pilot) watching the Pneumatic Duct Pressure Indicator]. In the early 1980s, the automated form of alerting mechanism (Start Valve OPEN) was absent on some operators aircraft.
Their operator's MEL (or MxProcedure) likely doesn't mention anything about "wiring shut" the Starter Valve. Worse, the DC-9’s JT8D’s Valve Position Indicator is hidden: located on the engine-side of Start Valve -- requiring an inspection mirror for actual visual verification of engine-mounted Valve Position INDICATOR. Since we have not had many cases recently (JT8D slowly goes to salvage), regulator and operators may have forgotten lessons of the ‘70’s and ‘80’s.
I can't find any major accident with JT8D due to Start Valve negligence, but here’s an analogous case on a Russian product:
Baikal Air/ 3Jan94 Tu-154M crashed near Irkutsk Airport in Siberia, BBC reported 111 pax and 9 crew (later "Flt Int'l" repts claimed 125 killed), reported #2 engine failure, lost control. P.C.= overspeed of engine STARTER Turbine Disc; disc broke-free, sawed through center engine. Tail mounted Engine caught fire, heat destroyed triplex hydraulic system. Crew had elected to takeoff DESPITE a warning-indication of a Starter unit malfunction (overspeed): crew disregarded the warning, convinced that the Starter Unit could NOT be still running. Starter: metal fragment (from the Starter Cooling radiator) JAMMED-OPEN the pneumatic start valve. (Later, CVR had crew discussing the warning light indicating overspeed of the engine starter; but it had illuminated 2 minutes after start. Captain decided to proceed with the flight, aircraft manual only addressed such a warning during Start. Discussion also included references to the airlines difficulty in getting another aircraft. ["ORAP" = Society of Air Accident Investigators, in Russia.]
For the JT8D, the Starter Valve ANNUNCATION failure presents varying a MEL/MxProcedure -- differing for that light failed ON (illuminated); vs failed OFF (extinguished) [80-1]; or the third case of the Valve inoperative [80-2].
About ten years ago the FAA admitted to some lack of agency "COMPETENCY" while reviewing a Douglas-- JT8D incident, re' MEL oversight:
= = = \/ = = = EXCERPT = = = \/ = = =
ACCIDENT AND INCIDENT DATABASE
Report Number: 19961217044949C
17-DEC-96, AUSTIN, NWA, DC-9-31, 9605 ...
“... START VALVE STAYED OPEN AFTER #2 ENGINE WAS STARTED.
“MAINTENANCE CLOSED THE VALVE MANUALLY AS PER MEL 80-2 AND 80-1.
“AFTER TAKE OFF AND DURING CLIMB, THE START VALVE AGAIN OPENED INTERMITTENTLY. THE STARTER THEN DISENTEGRATED DOING DAMAGE TO THE ENGINE COWLING AND CAUSING A FIRE. ENGINE WAS SHUT DOWN, AGENT DISCARDED [sic] AND AIRCRAFT RETURNED TO AUSTIN.
“ IT WAS DISCOVERED THAT NWAA APPROVED MEL HAS NO PROVISION TO ELECTRICALLY ISOLATE THE STARTER CONTROL VALVE.
“AGENCY COMPETENCY. MEL HAS NO PROVISION TO ELECTRICALLY ISOLATE THE STARTER CONTROL VALVE AS ALL OTHER CARRIERS HAVE.” [accusing words quoted from FAA dB]