Narrative:

After landing while making second 90 degree turn to taxi back; captain had difficulty steering aircraft. Observed both brake accumulators half depleted; both hydraulic pressure low lights illuminated; both hydraulic pressure gauges 200-300 psi and both hydraulic quantity gauges abnormally high (16-18 quarts). Stopped aircraft using accumulator braking and called for ground support to check for hydraulic leaks; pin gear and tow aircraft. [We] consulted QRH for appropriate hydraulic procedure. Three of four procedures in hydraulic section seemed to apply: (1) 'loss of both hydraulic systems or landing with no hydraulic pressure' (2) 'left (and/or) right hydraulic press low light' and (3) 'left (and/or right) quantity low or decreasing or abnormal high.' since we had no hydraulic pressure in either system; option (1) seemed to be the best choice. Before we could run the checklist; flight attendants in the back called to ask if we could hear the 'screaming mechanical noise' they were hearing. We figured the noise was a coming from the auxiliary hydraulic pump; so we turned it off. The noise stopped. Since both hydraulic quantity gauges were abnormally high; we also turned off the transfer pump. With the transfer pump off; left system pressure went to 0 psi and left quantity remained abnormally high. Right system hydraulic pressure and quantity returned to normal. We turned off the left engine pump and shut down the left engine. Ground personnel reported no leaks; pinned the gear and towed us to gate. We did not start the APU; but kept right engine running for pack cooling (100 degrees OAT). This was an abnormal mechanical problem (three good pumps; good transfer system; no loss of hydraulic fluid; yet complete loss of hydraulic pressure in both systems) and confusion results with appropriate checklist selection. In the first case; we had some sort of hydraulic foaming issue that rendered both hydraulic systems inoperable. The other issue was with the checklist. The first checklist in the hydraulic section is 'loss of both hydraulic systems or landing with no hydraulic pressure.' seemed like the correct checklist for our situation; however; if we had run this one; we would have never discovered that we had a good right system because the first step is to turn off all hydraulic pumps. This checklist procedure is confusing because it appears to be a combination of two separate checklists that were in the previous version of the old QRH. Additionally; 'loss of both hydraulic systems or landing with no hydraulic pressure' is listed as a 'non-alerted' procedure. However; you would be alerted to the loss of both hydraulic systems by the two 'hydraulic pressure low' lights. Suggest that the title of this procedure be changed to eliminate the 'loss of both hydraulic systems' verbiage in the title and simply be called 'landing with no hydraulic pressure.' this will keep people from running this checklist when one of the others would be more appropriate. If this checklist is retained with the present title; then step one of the checklists should read; 'transfer hydraulic pumps switch….off;' check both systems quantity and pressure. Then if both systems are still inoperative; turn off the remaining pumps. In addition to some confusion with running the correct checklist; we also had questions about APU usage and taxiing to the gate. Notes for 'loss of both hydraulic systems or landing with no hydraulic pressure' say 'unless APU operation is essential; shut down or do not start the APU in the event of hydraulic fluid loss.' the procedure for 'left (and/or) right hydraulic press low light' doesn't address APU usage at all; the procedure for 'left (and/or) right quantity low or decreasing or abnormal high says 'confirm APU air switch off during ground operations.' since all three of these procedures could be associated with a loss of hydraulic fluid; recommend they all say the same thing concerning APU usage. The final issue that came up during this event was under what situations should the aircraft be taxied with one hydraulic system. The checklist says that nosewheel steering 'may be restricted' on a single system; but none of our procedures provide guidance on whether we are expected to simply clear the runway or taxi all the way to the gate. The wording in 'left (and/or) right hydraulic press low light' implies that taxiing is ok by saying for a right system failure: 'after landing and before taxing: stop aircraft on the runway; install gear pins and close main doors.' taxiing with 'restricted' nosewheel steering (which can be caused by loss of either system) may not the safest course of action; yet the checklist does not prohibit and even seems to encourage taxiing once the gear is pinned and doors retracted after right hydraulic system failure. Suggest that company provide clear guidance on what they want us to do: stop and tow the aircraft; taxi clear of the runway; or taxi to the gate with a 'restricted' system.

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Original NASA ASRS Text

Title: Both MD80 hydraulic system reservoirs foamed and after landing both system pressures went to zero and quantities increased to 16-18 quarts. The Hydraulic System Failure checklists confused the situation because after the transfer pump was turned off; right system pressure returned to normal; the left did not.

Narrative: After landing while making second 90 degree turn to taxi back; Captain had difficulty steering aircraft. Observed both brake accumulators half depleted; both hydraulic pressure low lights illuminated; both hydraulic pressure gauges 200-300 PSI and both hydraulic quantity gauges abnormally high (16-18 quarts). Stopped aircraft using accumulator braking and called for ground support to check for hydraulic leaks; pin gear and tow aircraft. [We] consulted QRH for appropriate hydraulic procedure. Three of four procedures in hydraulic section seemed to apply: (1) 'Loss of Both Hydraulic Systems or Landing with NO Hydraulic Pressure' (2) 'Left (and/or) Right Hydraulic PRESS LOW Light' and (3) 'Left (and/or Right) Quantity Low or Decreasing or Abnormal High.' Since we had no hydraulic pressure in either system; option (1) seemed to be the best choice. Before we could run the checklist; Flight Attendants in the back called to ask if we could hear the 'screaming mechanical noise' they were hearing. We figured the noise was a coming from the auxiliary hydraulic pump; so we turned it off. The noise stopped. Since both hydraulic quantity gauges were abnormally high; we also turned off the transfer pump. With the transfer pump off; left system pressure went to 0 PSI and left quantity remained abnormally high. Right system hydraulic pressure and quantity returned to normal. We turned off the left engine pump and shut down the left engine. Ground personnel reported no leaks; pinned the gear and towed us to gate. We did not start the APU; but kept right engine running for pack cooling (100 degrees OAT). This was an abnormal mechanical problem (three good pumps; good transfer system; no loss of hydraulic fluid; yet complete loss of hydraulic pressure in both systems) and confusion results with appropriate checklist selection. In the first case; we had some sort of hydraulic foaming issue that rendered both hydraulic systems inoperable. The other issue was with the checklist. The first checklist in the hydraulic section is 'Loss of Both Hydraulic Systems or Landing with NO Hydraulic Pressure.' Seemed like the correct checklist for our situation; however; if we had run this one; we would have never discovered that we had a good right system because the first step is to turn off all hydraulic pumps. This checklist procedure is confusing because it appears to be a combination of two separate checklists that were in the previous version of the old QRH. Additionally; 'Loss of Both Hydraulic Systems or Landing with NO Hydraulic Pressure' is listed as a 'Non-Alerted' procedure. However; you would be alerted to the loss of both hydraulic systems by the two 'HYD Pressure Low' lights. Suggest that the title of this procedure be changed to eliminate the 'Loss of Both Hydraulic Systems' verbiage in the title and simply be called 'Landing with NO Hydraulic Pressure.' This will keep people from running this checklist when one of the others would be more appropriate. If this checklist is retained with the present title; then step one of the checklists should read; 'Transfer Hydraulic Pumps Switch….Off;' check both systems quantity and pressure. Then if both systems are still inoperative; turn off the remaining pumps. In addition to some confusion with running the correct checklist; we also had questions about APU usage and taxiing to the gate. Notes for 'Loss of Both Hydraulic Systems or Landing with NO Hydraulic Pressure' say 'Unless APU operation is essential; shut down or do not start the APU in the event of hydraulic fluid loss.' The procedure for 'Left (and/or) Right Hydraulic PRESS LOW Light' doesn't address APU usage at all; the procedure for 'Left (and/or) Right Quantity Low or Decreasing or Abnormal High says 'Confirm APU Air Switch OFF during ground operations.' Since all three of these procedures could be associated with a loss of hydraulic fluid; recommend they all say the same thing concerning APU usage. The final issue that came up during this event was under what situations should the aircraft be taxied with one hydraulic system. The checklist says that nosewheel steering 'may be restricted' on a single system; but none of our procedures provide guidance on whether we are expected to simply clear the runway or taxi all the way to the gate. The wording in 'Left (and/or) Right Hydraulic PRESS LOW Light' implies that taxiing is OK by saying for a right system failure: 'after landing and before taxing: Stop aircraft on the runway; install gear pins and close main doors.' Taxiing with 'restricted' nosewheel steering (which can be caused by loss of either system) may not the safest course of action; yet the checklist does not prohibit and even seems to encourage taxiing once the gear is pinned and doors retracted after right hydraulic system failure. Suggest that Company provide clear guidance on what they want us to do: stop and tow the aircraft; taxi clear of the runway; or taxi to the gate with a 'restricted' system.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.