A First Officer and Captain report noticing during Takeoff and other phases of flight; the EPR and Minimum N-1 displayed values at all times to be slightly less than what would normally be expected and less than the numbers published in their Quick Reference Handbook (QRH). The MD-83 Thrust Rating Panel (TRP) indicated -217 engines were installed; not the expected -219 series engines.
Synopsis
A First Officer and Captain report noticing during Takeoff and other phases of flight; the EPR and Minimum N-1 displayed values at all times to be slightly less than what would normally be expected and less than the numbers published in their Quick Reference Handbook (QRH). The MD-83 Thrust Rating Panel (TRP) indicated -217 engines were installed; not the expected -219 series engines.
Narrative
Problem first noticed on preflight. We fly so many different equipment variations and types that it is difficult to keep things straight. On preflight; the Captain verbalized to me that the Thrust Rating Panel (TRP) tested properly for a -217 MD80 engine; rather than a -219 (and EPR Limit value of 2.04 vs. 2.08 during the test). His conclusion was that this MD80 must have the -217 engine. During the subsequent Takeoff roll on a short wet runway; I noticed the EPR Limit value was slightly low and the N1 value for one engine was slightly below the prescribed minimum value for the takeoff. I made a quick decision that if I were to verbalize what I saw; in the time it took for us to make a decision about the slightly low thrust values; we would have already accelerated through the minimum speed we had established for a Rejected Takeoff (RTO); during my takeoff briefing. Additionally; the runway was very wet; making a Rejected Takeoff additionally hazardous. The Takeoff was made normally and at an appropriate time during the climb; I asked the Captain if he had noticed the low N1 and EPR values that I had seen during the Takeoff. He then remembered what he had said about the TRP test. The Captain then recalled where to check the engine type for the aircraft in the FMS Computer. We could then see that the actual engines equipped should be the -219s. For the remainder of the flight; we monitored the EPR Limit value being displayed and compared it to values published in the Quick Reference Handbook (QRH) for the appropriate phase of flight. We found the displayed values at all times to be slightly less than what would normally be expected and less than the numbers published in the QRH. After arrival in ZZZ; the Captain called company Maintenance to question the problem and had the TRP deferred. It was his opinion that the incorrect Thrust Rating Panel had been installed on the aircraft.
Second reporter narrative
On preflight I noticed Thrust Rating Panel (TRP) tested OK for a -217 MD-80; I tried to determine what engines we had; then got distracted and moved on. I assumed we had -217 engines. On Takeoff from a short wet runway in rain; my First Officer (FO) noticed EPR and Minimum N-1 values slightly low. I did not notice a problem; no verbalization occurred due to runway conditions and speeds; and takeoff was successful. On climb out we both noticed EPR limit was lower than normal. At this point my FO told me he had noticed on Takeoff previously mentioned discrepancy. Here is where I finally remembered where to check on the FMS for engines; I now realized that the aircraft should be equipped with -219 engines. We monitored the EPR limits and N1's all the way to ZZZ. All Manuals in the airplane are for -219 engines and all looked at by the FO and on his side. In ZZZ; I called Maintenance Control to report the problem of slightly low EPR on Takeoff and the TRP (Thrust Rating Panel) was deferred. Part of the problem is that my company is very disorganized; we fly many different planes obtained from different companies. Many of our airplane configurations are completely different and there is no consistency. I should have stopped when I saw the initial discrepancy and called company Maintenance to question the problem. Perhaps ego played a part as I did not want to admit I did not know where to determine what engine our aircraft had. I believe the wrong TRP was installed in this aircraft.
NASA callback
Reporter stated all the Manuals in the Cockpit were based on the MD-83 having -219 series engines. But when they did a Press to Test function on the Thrust Rating Panel (TRP) for engine Take-off EPR values; the numbers 2.04 EPR would show indicating they had -217 engines on the aircraft; not the -219's with an expected 2.08 EPR reading on the TRP panel.Reporter stated Maintenance informed him the Performance values can be changed by adjusting or changing some unit; possibly the Fuel Control; to allow the same engine to meet -219 values. The TRP panel is a deferrable MEL item because Pilots can manually set EPR while monitoring during different flight phases.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.