Narrative:

During the originating check the stabilizer CH1 would not engage. I called maintenance. We troubleshot the system including two reset attempts to no avail. I wrote it up and proceeded to deplane and wait for contract maintenance. After being unable to resolve the anomaly; it was determined that a group one ferry was required to get the aircraft to maintenance. After the ferry paperwork was received; the conference call took place wherein I made the following concerns known. When conducting this ferry we followed the 'ferry flight supplemental procedures with stabilizer channel 1 inoperative' in that procedure it requires the inoperative stabilizer channel circuit breaker [circuit breaker] to be pulled. In this case; it was circuit breaker 2f5.as a result of pulling this circuit breaker; the mach trim went offline and would not re-engage. No where in the supplemental procedures did it mention that the mach trim would come offline. The systems manual OM vol. Ii section 11 in fact states clearly that only one channel of the stabilizer trim system is required to be engaged for the mach trim to be engaged and operative. Maintenance control addressed this by suggesting we defer the mach trim under the MEL. We expressed my reservations with this solution as this piece of equipment was not listed on the ferry permit as inoperative. Maintenance said that they would have the mach trim listed on a new ferry permit as well as the stabilizer channel 1 inoperative in addition to having contract maintenance defer the mach trim. While waiting for this new paperwork; I researched more closely the maintenance history of this aircraft and found numerous write ups of stabilizer channel 1. The corrective actions in these write ups were addressed by replacing numerous components in the stabilizer system. Given this fact and the added fact that nowhere in our operating manual does it state that mach trim will not work or be operative with only one of the stabilizer channels being out. I decided that during the second conference call I would call attention again to this point and ask for clarification from maintenance with documentation detailing that this was a normal operating characteristic given the stabilizer channel 1 was inoperative. As maintenance was unable to produce documentation stating why the mach trim would be inoperative with stabilizer channel 2 operative and engaged; I concluded that there was potentially additional problems with the stabilizer trim system that rendered the aircraft unsafe to operate.there were many threats in this scenario: the supplemental procedure did not address the mach trim. The supplemental procedure did not address what happens when the circuit breaker 2f5 is pulled that we would lose the mach trim. Our vol ii specifically says that the mach trim will be operative with 1 stabilizer channel engaged and operative. Maintenance could not provide documentation or give us an accurate depiction of the system and what would happen when using the supplemental procedure. The ferry permit did no address the mach trim issue. The safety department agreed this was a difficult scenario. In learning from the event; I felt that it was an unclear procedure. The supplemental procedure did not address every scenario that occurred after following it exactly. I feel that with the data given and the supplemental procedure used it gave contradicting information to what our manual specifically says about the system. Our maintenance department could not give us a specific answer to the problem; but instead wanted to defer the mach trim. This is not a proper way to handle the situation especially when the supplemental procedure does not display it. Our safety department; in which I spoke an agent who then spoke with safety about the scenario agreed with us that the procedure did not accurately display what it should have and that there could be something wrong with the mach trim. We deemed that there was too much contradicting information via the procedure; maintenance; and what our specific guidance in the OM vol ii said. This deemed it unsafe to operate the aircraft under the confines we were given. They never did answer us in maintenance control nor give us documentation as to why we would lose the mach trim in this scenario when our manuals indicate otherwise.

Related reports:

Google
 

Original NASA ASRS Text

Title: A CRJ-200 crew found the STAB CH 1 would not engage during preflight; so agreed to a ferry flight for maintenance. But with the appropriate circuit breaker pulled the MACH TRIM became inoperative so the crew refused to fly because the aircraft's condition was ambiguous.

Narrative: During the Originating Check the STAB CH1 would not engage. I called Maintenance. We troubleshot the system including two reset attempts to no avail. I wrote it up and proceeded to deplane and wait for Contract Maintenance. After being unable to resolve the anomaly; it was determined that a Group One Ferry was required to get the aircraft to Maintenance. After the ferry paperwork was received; the conference call took place wherein I made the following concerns known. When conducting this ferry we followed the 'ferry flight supplemental procedures with STAB Channel 1 INOP' in that procedure it requires the inoperative STAB Channel CB [Circuit Breaker] to be pulled. In this case; it was CB 2F5.As a result of pulling this CB; the MACH Trim went offline and would not re-engage. No where in the supplemental procedures did it mention that the MACH trim would come offline. The systems manual OM Vol. II section 11 in fact states clearly that only one channel of the STAB trim system is required to be engaged for the MACH Trim to be engaged and operative. Maintenance Control addressed this by suggesting we defer the MACH trim under the MEL. We expressed my reservations with this solution as this piece of equipment was not listed on the ferry permit as inoperative. Maintenance said that they would have the MACH trim listed on a new ferry permit as well as the STAB Channel 1 INOP in addition to having Contract Maintenance defer the MACH Trim. While waiting for this new paperwork; I researched more closely the maintenance history of this aircraft and found numerous write ups of STAB Channel 1. The corrective actions in these write ups were addressed by replacing numerous components in the STAB system. Given this fact and the added fact that nowhere in our operating manual does it state that MACH Trim will not work or be operative with only one of the STAB Channels being out. I decided that during the second conference call I would call attention again to this point and ask for clarification from Maintenance with documentation detailing that this was a normal operating characteristic given the STAB channel 1 was inoperative. As maintenance was unable to produce documentation stating why the MACH Trim would be inoperative with STAB Channel 2 operative and engaged; I concluded that there was potentially additional problems with the STAB Trim system that rendered the aircraft unsafe to operate.There were many threats in this scenario: The supplemental procedure did not address the MACH Trim. The supplemental procedure did not address what happens when the CB 2F5 is pulled that we would lose the MACH Trim. Our Vol II specifically says that the MACH Trim will be operative with 1 STAB Channel engaged and operative. Maintenance could not provide documentation or give us an accurate depiction of the system and what would happen when using the supplemental procedure. The ferry permit did no address the MACH Trim issue. The safety department agreed this was a difficult scenario. In learning from the event; I felt that it was an unclear procedure. The supplemental procedure did not address every scenario that occurred after following it exactly. I feel that with the data given and the supplemental procedure used it gave contradicting information to what our Manual specifically says about the system. Our Maintenance Department could not give us a specific answer to the problem; but instead wanted to defer the MACH Trim. This is not a proper way to handle the situation especially when the supplemental procedure does not display it. Our Safety department; in which I spoke an Agent who then spoke with Safety about the scenario agreed with us that the procedure did not accurately display what it should have and that there could be something wrong with the MACH Trim. We deemed that there was too much contradicting information via the procedure; Maintenance; and what our specific guidance in the OM Vol II said. This deemed it unsafe to operate the aircraft under the confines we were given. They never did answer us in Maintenance Control nor give us documentation as to why we would lose the MACH Trim in this scenario when our manuals indicate otherwise.

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.