Narrative:

Flight was parked at gate. During the preflight walk around we encountered a hydraulic leak on [the aircraft]. I was the captain and was receiving a line-check examination from [another captain] who was the line check pilot (lcp). [A second captain] was the aircrew program designee (apd) and also giving a line check examination. During the post-flight walk-around; the lcp found that hydraulic fluid was dripping from the left main landing gear door; creating a small pool of fluid on the concrete below the gear door. I photographed the leak and sent it to mx control for examination while they notified our outstation mechanic. Our mechanic arrived within 30 min. And I showed him the leak. He confidently agreed that it was hydraulic fluid and said he'd call our mx control and let us know what they wanted him to do. After talking to mx control the mechanic came up into the cabin and informed us that the leak was just dirty water. Both the lcp and the apd looked to me and I replied that I don't think it's just dirty water; and I also asked them what they thought. I had already smelled the fluid and touched it to assess the viscosity. However; since the examining captains were deferring the judgement to me; and also since I'm not the mechanical expert; I deferred to the expertise of our mechanic and maintenance controllers. The mechanic said that it was indeed just dirty water and proceeded to his van to clear the write-up.in the interim I again asked both examiners what they thought and after some deliberation our lcp said he would like to see what happens after pressurizing the hydraulic system and I agreed. I told our mechanic what we needed to see and he also agreed. After turning on the hydraulic pumps to pressurize the system and additionally extending the flaps and spoilers; there was no initial evidence of leaks. However; just after the call had been made to clear the write-up; I took a second look and saw a new fluid pattern on the concrete and a rivulet of purplish fluid running down the underside of the wing from an inspection hole. This was not mistaken for dirty water but was correctly identified by our mechanic as hydraulic fluid.our mechanic again notified our maintenance control and an investigation into the source of the leak was initiated. Our passengers were transferred to a different aircraft for a delayed flight.in reviewing the event; we definitely felt like our outstation mechanic was influenced to change his initial opinion about the hydraulic leak after talking to our mx control and that we were all being pushed by our maintenance control and operations control to get this plane back into service in an un-safe manner. I think that the causes of this problem go much deeper than our maintenance and operational controllers simply being pressured into keeping the planes departing on-time. New captains and mechanics also enable this pressure by accepting these 'pencil-whipped' aircraft. But these are mere symptoms of a deeper problem. A safety culture comes from experienced individuals at every level; who understand how to hold the line and administer the hard-won safety standards and policies of an industry. I think that the problems we are having with the increased number of maintenance issues; ie. Mis-diagnosis of mechanical discrepancies and the resulting operational pressures that ensue due to increased downtime on valuable airframes; are being driven by unrepaired structural damage to the regional airline industry. The ever-diminishing experience level of personnel at the regional airlines in general is the visible result of a damaged industry.from management down to the front-line pilots; mechanics; flight attendants and ramp agents; the past safety culture that developed from experienced individuals is being depleted and forgotten as those experienced people leave the regional airlines for higher pay and quality of life at better run mainline companies. The experience stays at the mainline but cannot be transferred backward to the regionals. Nor is quality of life improving enough to keep the 'old heads' at the regional airlines.I suggest that mainline airlines take full responsibility for the structural damage they are creating in the regional airlines and work to repair the safety culture by compensating all experienced individuals enough to stay and lead the new airline employees. Stop the brain drain and you stop the degradation of safety.on a simpler; more immediate level; our operations/maintenance controllers and pilots need to be taught how to slow down; reject pilot-pushing and accept cancellations and delays as part of the new industrial normal at these regional companies. That may help to relieve some of the pressure to overlook a broken hydraulic line by calling it 'just dirty water'.

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Original NASA ASRS Text

Title: The Captain of a Bombardier CRJ-900 reported evidence of hydraulic fluid dripping from the left main landing gear door. Maintenance called it 'dirty water'; but it was verified that was indeed hydraulic fluid.

Narrative: Flight was parked at gate. During the preflight walk around we encountered a hydraulic leak on [the aircraft]. I was the captain and was receiving a line-check examination from [another Captain] who was the Line Check Pilot (LCP). [A second Captain] was the Aircrew Program Designee (APD) and also giving a line check examination. During the post-flight walk-around; the LCP found that hydraulic fluid was dripping from the left main landing gear door; creating a small pool of fluid on the concrete below the gear door. I photographed the leak and sent it to mx control for examination while they notified our outstation mechanic. Our mechanic arrived within 30 min. and I showed him the leak. He confidently agreed that it was hydraulic fluid and said he'd call our mx control and let us know what they wanted him to do. After talking to mx control the mechanic came up into the cabin and informed us that the leak was just dirty water. Both the LCP and the APD looked to me and I replied that I don't think it's just dirty water; and I also asked them what they thought. I had already smelled the fluid and touched it to assess the viscosity. However; since the examining captains were deferring the judgement to me; and also since I'm not the mechanical expert; I deferred to the expertise of our mechanic and maintenance controllers. The mechanic said that it was indeed just dirty water and proceeded to his van to clear the write-up.In the interim I again asked both examiners what they thought and after some deliberation our LCP said he would like to see what happens after pressurizing the hydraulic system and I agreed. I told our mechanic what we needed to see and he also agreed. After turning on the hydraulic pumps to pressurize the system and additionally extending the flaps and spoilers; there was no initial evidence of leaks. However; just after the call had been made to clear the write-up; I took a second look and saw a new fluid pattern on the concrete and a rivulet of purplish fluid running down the underside of the wing from an inspection hole. This was not mistaken for dirty water but was correctly identified by our mechanic as hydraulic fluid.Our mechanic again notified our maintenance control and an investigation into the source of the leak was initiated. Our passengers were transferred to a different aircraft for a delayed flight.In reviewing the event; we definitely felt like our outstation mechanic was influenced to change his initial opinion about the hydraulic leak after talking to our mx control and that we were all being pushed by our maintenance control and operations control to get this plane back into service in an un-safe manner. I think that the causes of this problem go much deeper than our maintenance and operational controllers simply being pressured into keeping the planes departing on-time. New captains and mechanics also enable this pressure by accepting these 'pencil-whipped' aircraft. But these are mere symptoms of a deeper problem. A safety culture comes from experienced individuals at every level; who understand how to hold the line and administer the hard-won safety standards and policies of an industry. I think that the problems we are having with the increased number of maintenance issues; ie. mis-diagnosis of mechanical discrepancies and the resulting operational pressures that ensue due to increased downtime on valuable airframes; are being driven by unrepaired structural damage to the regional airline industry. The ever-diminishing experience level of personnel at the regional airlines in general is the visible result of a damaged industry.From management down to the front-line pilots; mechanics; flight attendants and ramp agents; the past safety culture that developed from experienced individuals is being depleted and forgotten as those experienced people leave the regional airlines for higher pay and quality of life at better run mainline companies. The experience stays at the mainline but cannot be transferred backward to the regionals. Nor is quality of life improving enough to keep the 'old heads' at the regional airlines.I suggest that mainline airlines take full responsibility for the structural damage they are creating in the regional airlines and work to repair the safety culture by compensating all experienced individuals enough to stay and lead the new airline employees. Stop the brain drain and you stop the degradation of safety.On a simpler; more immediate level; our operations/maintenance controllers and pilots need to be taught how to slow down; reject pilot-pushing and accept cancellations and delays as part of the new industrial normal at these regional companies. That may help to relieve some of the pressure to overlook a broken hydraulic line by calling it 'just dirty water'.

Data retrieved from NASA's ASRS site 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.