Date: 201205
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
ATC / advisory: Tower ZZZ
Aircraft component: Turbine Engine Thrust Reverser
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Pre-flight
Result: General None Reported / Taken
Contributing factors: Aircraft; Procedure; MEL; Human Factors
Primary problem: Ambiguous

Narrative: Aircraft had MEL 78-1 sit 1 which was on our release. The right thrust reverse lever was tied down. The left thrust reverser was operating normally. The MEL for this procedure is quite lengthy due to so many options/items listed in the 'action required' column. Upon further review of this during our flight it seems we should have applied a takeoff performance weight reduction related to the right thrust reverse lever being tied down. If so; we took off overweight for the length of the runway with a temperature of 10 C and calm winds. The MEL states that both thrust reverse levers are required to make the auto brakes and spoilers deploy on a rejected takeoff (RTO) as noted in the MEL Manual item E. On airplanes with the Auto Spoiler RTO mode; automatic spoiler deployment for takeoff will not occur unless both Reverser Levers are moved to the reverse idle position. On these aircraft; if affected Reverser Lever has been secured down to prevent its use; auto spoilers may still be armed for takeoff; but flight crew must manually pull handle aft upon initiation of an RTO to deploy spoilers. If affected Reverser Lever has not been secured down; normal takeoff/RTO procedures may be used on DC-9 aircraft with Mechanical Latches... This seems to be specific to DC-9 aircraft only and not to DC-9-8x aircraft. Should this even be in our MEL book as we have no DC-9 aircraft in our fleet? In any case; it appears the thrust reverse lever should not have been (nor should it ever be) tied down on an MD8x (DC-9-8x) aircraft. There is much conflicting information in our AOM and ASM related to item E.If RTO capability is not used as a result of a MEL; the spoiler handle must be fully retracted. The last sentence which states; 'If RTO capability is not used as a result of a MEL; the spoiler handle must be fully retracted.' This is a contradiction of both what the MEL in item E. says and what is listed in the ASM; which states: 4. ABS Takeoff Mode a. The takeoff mode is armed by selecting T.O. on the AUTO BRAKE selector and placing the ARM-DISARM switch in the ARM position. b. In the takeoff mode; both auto spoilers and auto brakes must be armed. Advancing throttles for take off with either system not armed will activate the takeoff warning. When one automatic system is deferred for takeoff; the other automatic system will also be deactivated for takeoff. In this situation; both manual spoilers and full antiskid braking are still available and the takeoff performance is not affected. The last sentence states; 'The takeoff performance is not affected.' which contradicts what our ATOGS appear to indicate. Upon arrival I called Dispatch to let them know what had happened. He transferred me to Maintenance Control and I told them what had happened as well. Maintenance Control said the right reverse lever should not have been tied down and it would be corrected overnight. Clean up MEL 78-1 and add a note at the very top of the FIRST page of the actions required column; which states something like: 'CAUTION: BOTH thrust reverse levers must be used for the auto RTO to function. If auto RTO is not available a performance reduction for takeoff weight must be applied.' Note that I'm assuming this is the case for both thrust levers; due to what the MEL says. I could not find this specifically in the MD80 AOM or ASM. The AOM; and ASM; and MEL Manual (and any other manuals such as the maintenance manual that we don't have on the aircraft) should all agree on this subject without conflicting and confusing information.




Synopsis: MD83 Captain questions MEL 78-1 which was applied to his aircraft by locking out the right thrust reverser and tying down the reverse lever. He believes a performance decrement should have been taken due to no RTO function.