Jet Ranger All Series Undifferentiated or Other Model
Situational Awareness; Training / Qualification
Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Company Policy; Manuals; Procedure
Required maintenance/inspection interval was inadvertently overflown. Upon investigation of the cause of the overflight the following root causes were identified. Bell 505 maintenance was developed in accordance with the MSG-3 methodology (Maintenance Steering Group-3). Different than other helicopters/airplanes that we have operated this method does not permit any tolerance for hourly inspection intervals and requires calendar based maintenance actions be conducted to the day rather than the calendar month. For example; a 1 year inspection conducted on May 3; 2019 is required on May 3; 2020 - not May 30 like many other aircraft. A review of the Bell 505 Maintenance Manual found that this information is present in the manual but is in the definitions section not in Chapter 5 where other manufacturer's include the data. The previous operator of the aircraft was not properly utilizing the block provided on each page of the aircraft log to record next maintenance due date and time information. This block is used on other aircraft to convey this information to the flight crew. It is unknown why flight crews and maintenance personnel did not utilize this block in the same manner that is done for the other helicopters. Maintenance planned to operate the aircraft up to 110 hours flight time since the last 100 hour inspection (10% overage as is allowed for other helicopters) or through 7/31/2020 (12 calendar months since last 1 year inspection) whichever came first. [Before the end of July] we made aware by the Bell Tech representative of the date and hour tolerances (none) for the 505 and operations were stopped until maintenance was completed.
During an aircraft records check by Quality Assurance Inspectors; it was found that an aircraft maintained under MSG-3 methodology was instead maintained under MSG-2; causing overflights of many required checks.