Narrative:

After reaching cruising altitude of FL390; the first officer adjusted power to maintain mach .77. We were at this altitude for a total of 16 minutes before initial descend to destination. During 12 of those minutes we had a total of 7 power variations/fluctuations in the lh engine with a loss of 3% of N1; 25 degrees and an increase of 20 psi in the bleed system indicated in the ecs page of the ED2. These indications came with a subtle yaw and sound from the engine area. There were no other variations of indications: neither EICAS messages or any other engine parameter change were indicated. The captain consulted the non-EICAS abnormal procedures for guidance. However; there were not any procedures that cover the specific situation that was taking place. The first officer consulted the odh for drift down procedures; in case they need to be used. The captain sent an ACARS message to dispatch explaining the situation. Shortly after; initial descent was started and no other event took place. 5 minutes later; dispatch responded that maintenance control had been notified; suggested consulting the pilot handbook for procedures and to make a decision was up to the flight crew. The captain talked to the cabin crew to obtain more information. The cabin crew had not noticed anything abnormal. At that moment; we were less than 30 minutes to destination and the flight was completed with no further occurrence. Once on the ground; the captain entered a discrepancy in the maintenance log and notified dispatch and maintenance control. The captain talked to maintenance control supervisors and fleet manager to assist with additional information. The captain agreed to collaborate and help with system checks which could be necessary to determine or fix the problem. The field conditions were deteriorating to reported visibility of 1/8 mile; ovc 001; night conditions and the longest available runway was 6548 feet long. After 1.5 hours waiting on the aircraft; two non air carrier mechanics came on board to assist us. The captain was given a set of photocopies with 3 different maintenance procedures and told to follow those procedures. Also; that problem was common and easy to check and would take just a few minutes to get resolved. Everything was probably due to a pack problem. After a brief phone conversation with the fleet manager and a maintenance control supervisor; the captain agreed to help and assist; but not to take the primary roll in determining what the problem was following maintenance procedures. While the above conversation was taking place; the mechanics maintained a conversation accusing the captain of not wanting to help and not wanting to 'do it.' the first officer and cabin crew could clearly hear this conversation. For some reason; these mechanics left the aircraft. At that time the station supervisor came on board and said the space we were occupying at the gate needed to be used by a different inbound aircraft. They suggested to taxi the plane across the field to the FBO where engine tests could also take place. We briefed the security procedures for returning the plane to the terminal and we agreed to do it. The captain agreed to taxi the aircraft since the station supervisor said that towing the aircraft would cause delays to everybody else and they were under staffed. The fleet manager authorized the captain to taxi the aircraft to this remote location in the field. At that time; the cabin crew left the aircraft and waited for the flight crew in the terminal. Maintenance mechanics returned to the aircraft and we briefed the following process: the flight crew would taxi the aircraft to the FBO. They would meet us at the FBO; we would request taxi to a safe area in the airport where the testing could take place and these mechanics would guide the flight crew in every procedure. Ground control gave us a non-active runway for the tests; mechanics and flight crew completed two maintenance procedures which include various changes in both the air conditioning and bleed air control panels. During these testing; the first officer was in charge of communication s with ATC and brakes/position/movement of the aircraft; while the captain assisted the mechanics. Every action the flight crew followed in these system checks; everything was indicated to us in written form; and guided by the mechanic on board. The flight crew refused to perform some of the petitions of the mechanics because these requests were not described or available in any form to the flight crew. Example: the captain was asked to increase thrust levers to toga; or high power settings to check the system in that setting. Furthermore; we were requested to perform a high speed taxi. After the testing was completed we taxied to the FBO where the discrepancy was cleared.

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Original NASA ASRS Text

Title: A CRJ900 developed engine RPM; Thrust and ITT fluctuations at cruise. After landing extensive troubleshooting was needed using Contract Maintenance and the Flight Crew; reluctantly performing some maintenance tasks; in order to determine that the most probable cause was a Pack.

Narrative: After reaching cruising altitude of FL390; the First Officer adjusted power to maintain MACH .77. We were at this altitude for a total of 16 minutes before initial descend to destination. During 12 of those minutes we had a total of 7 power variations/fluctuations in the LH engine with a loss of 3% of N1; 25 Degrees and an increase of 20 psi in the Bleed System indicated in the ECS page of the ED2. These indications came with a subtle yaw and sound from the engine area. There were no other variations of indications: Neither EICAS messages or any other engine parameter change were indicated. The Captain consulted the Non-EICAS Abnormal procedures for guidance. However; there were not any procedures that cover the specific situation that was taking place. The First Officer consulted the ODH for drift down procedures; in case they need to be used. The Captain sent an ACARS MSG to Dispatch explaining the situation. Shortly after; initial descent was started and no other event took place. 5 minutes later; Dispatch responded that Maintenance Control had been notified; suggested consulting the Pilot Handbook for procedures and to make a decision was up to the flight crew. The Captain talked to the cabin crew to obtain more information. The cabin crew had not noticed anything abnormal. At that moment; we were less than 30 minutes to destination and the flight was completed with no further occurrence. Once on the ground; the Captain entered a discrepancy in the Maintenance Log and notified Dispatch and Maintenance Control. The Captain talked to Maintenance Control Supervisors and Fleet Manager to assist with additional information. The Captain agreed to collaborate and help with system checks which could be necessary to determine or fix the problem. The field conditions were deteriorating to reported visibility of 1/8 mile; OVC 001; night conditions and the longest available runway was 6548 feet long. After 1.5 hours waiting on the aircraft; two non air carrier mechanics came on board to assist us. The Captain was given a set of photocopies with 3 different maintenance procedures and told to follow those procedures. Also; that problem was common and easy to check and would take just a few minutes to get resolved. Everything was probably due to a Pack problem. After a brief phone conversation with the Fleet Manager and a Maintenance Control Supervisor; the Captain agreed to help and assist; but not to take the primary roll in determining what the problem was following maintenance procedures. While the above conversation was taking place; the Mechanics maintained a conversation accusing the Captain of not wanting to help and not wanting to 'do it.' The First Officer and cabin crew could clearly hear this conversation. For some reason; these Mechanics left the aircraft. At that time the Station Supervisor came on board and said the space we were occupying at the gate needed to be used by a different inbound aircraft. They suggested to taxi the plane across the field to the FBO where engine tests could also take place. We briefed the security procedures for returning the plane to the terminal and we agreed to do it. The Captain agreed to taxi the aircraft since the Station Supervisor said that towing the aircraft would cause delays to everybody else and they were under staffed. The Fleet Manager authorized the Captain to taxi the aircraft to this remote location in the field. At that time; the cabin crew left the aircraft and waited for the flight crew in the terminal. Maintenance Mechanics returned to the aircraft and we briefed the following process: The flight crew would taxi the aircraft to the FBO. They would meet us at the FBO; we would request taxi to a safe area in the airport where the testing could take place and these Mechanics would guide the flight crew in every procedure. Ground Control gave us a non-active runway for the tests; Mechanics and Flight Crew completed two maintenance procedures which include various changes in both the Air Conditioning and Bleed Air Control panels. During these testing; the First Officer was in charge of communication s with ATC and brakes/position/movement of the aircraft; while the Captain assisted the Mechanics. Every action the flight crew followed in these system checks; everything was indicated to us in written form; and guided by the Mechanic on board. The flight crew refused to perform some of the petitions of the mechanics because these requests were not described or available in any form to the flight crew. Example: The Captain was asked to increase thrust levers to TOGA; or high power settings to check the system in that setting. Furthermore; we were requested to perform a high speed taxi. After the testing was completed we taxied to the FBO where the discrepancy was cleared.

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.