Narrative:

While investigating vibration; there was an effort to focus on the attaching hardware of the vertical stabilizer and in preparing for the replacement of the attaching hardware; discovered that there was no call-out for torquing sequence in the aircraft maintenance manual (amm). Upon requesting additional technical data from gulfstream and israel aircraft industries (iai); we discovered that there was a significant disparity between the torque values listed in the amm and what was listed on the iai drawings (practically double the values): 1) our concern is that this information is not available in the amm as required to perform adequate maintenance in this area. Flag notes and important info is missing and places an undue burden on any operator or maintenance provider. More importantly is that gulfstream and iai have attached a financial obligation to the owner/ operator to obtain this information that should be contained in the amm. 2) the aft vertical stabilizer bracket securing bolts shall be torque first. There is no specific sequence of order in tightening. General practices have all the bolts brought up to torque; as evenly as possible to prevent any binding of the fitting joint. 3) note: the following items in the amm are incorrect. A) amm 55-30-00; figure 404; detail F; is labeled incorrectly. Detail F is the forward fitting and detail G is the aft fitting. The forward fitting is the only attachment that has a shim. B) the aft fitting bolts are torque to 1200 to 1600 lb-inches; the locking nuts are torque to 450 to 550 lb-inches. C) the forward fitting bolts are torque to 620 to 840 lb-inches; the locking nuts are torque to 450 to 550 lb-inches. 4) be sure to follow the amm procedures (except as noted above) and illustrated parts catalog (ipc) requirements and be aware that one bolt stack-up is different from the rest on the forward and aft attach brackets. 5) for further instruction contact technical operations.[recommend]:1) an investigation needs to be completed to determine if the proper torque value was applied during initial assembly of all G-200 aircraft. 2) require original equipment manufacturer (oem) to supply all technical data in amm for all operators and maintenance personnel to have access to. Maintenance inspector. Hangar. Structural [issue]. Aft [position].

Related reports:

Google
 

Original NASA ASRS Text

Title: An Aircraft Maintenance Inspector (AMI) reports there was significant disparity between the Torque Values listed in the Gulfstream G-200 Aircraft Maintenance Manual (AMM) for the Vertical Stabilizer attaching bolts compared to what was listed on the Israel Aircraft Industry (IAI) drawings for the same bolts; torque values were almost double.

Narrative: While investigating vibration; there was an effort to focus on the attaching hardware of the Vertical Stabilizer and in preparing for the replacement of the attaching hardware; discovered that there was no Call-Out for torquing sequence in the Aircraft Maintenance Manual (AMM). Upon requesting additional technical data from Gulfstream and Israel Aircraft Industries (IAI); we discovered that there was a significant disparity between the torque values listed in the AMM and what was listed on the IAI Drawings (practically double the values): 1) Our concern is that this information is not available in the AMM as required to perform adequate maintenance in this area. Flag notes and important info is missing and places an undue burden on any Operator or Maintenance Provider. More importantly is that Gulfstream and IAI have attached a financial obligation to the Owner/ Operator to obtain this information that should be contained in the AMM. 2) The Aft Vertical Stabilizer bracket securing bolts shall be torque first. There is no specific sequence of order in tightening. General practices have all the bolts brought up to torque; as evenly as possible to prevent any binding of the fitting joint. 3) Note: the following items in the AMM are incorrect. A) AMM 55-30-00; Figure 404; Detail F; is labeled incorrectly. Detail F is the forward fitting and Detail G is the aft fitting. The forward fitting is the only attachment that has a shim. B) The Aft fitting bolts are torque to 1200 to 1600 lb-inches; the locking nuts are torque to 450 to 550 lb-inches. C) The Forward fitting bolts are torque to 620 to 840 lb-inches; the locking nuts are torque to 450 to 550 lb-inches. 4) Be sure to follow the AMM procedures (except as noted above) and Illustrated Parts Catalog (IPC) requirements and be aware that one bolt stack-up is different from the rest on the Forward and Aft attach brackets. 5) For further instruction contact Technical Operations.[Recommend]:1) An investigation needs to be completed to determine if the proper torque value was applied during initial assembly of all G-200 aircraft. 2) Require Original Equipment Manufacturer (OEM) to supply all technical data in AMM for all Operators and Maintenance personnel to have access to. Maintenance Inspector. Hangar. Structural [Issue]. Aft [position].

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.