Hotel Mode Start events

An ATR operator has kindly shared with us the below Safety Bulletin. The topic was discussed during an operator safety forum. Another operator indicated they encountered a similar experience. This highlights again the benefit of sharing lessons learnt to increase safety margins across the fleet.

Our thanks to both operators for sharing the information.

Different root causes

Four events have been reported where engine 2 has been started by the flight crew without the propeller brake engaged. All of these engine starts were intended to be in HOTEL mode i.e. with the propeller brake engaged.
Usually, the propeller brake is engaged on aircraft arrival at the gate and remains engaged until released prior to taxi. In two of the four incidents, the inbound flight crew omitted engaging the propeller brake on arrival at the gate due to another distraction. A crew swap then took place and the outbound crew did not identify the propeller brake was disengaged before starting engine 2. In one of these two events, the engine
2 start was conducted upon the crew’s arrival to the flight deck, prior to any checklist completion, to aid in cabin cooling.
In the remaining two incidents, the inbound crew had arrived on the gate and engaged the propeller brake. This was confirmed by the outbound crew during their preflight walkaround check. However, engineering inspections of the propellers were required (one due delamination evidence and one due a possible bird strike). The engineer asked the flight crew to release the propeller brake to enable the inspection to be conducted. On completion of the work, the engineer returned the tech log to the crew, however they didn’t instruct the crew to reengage the propeller brake and this was missed by the crew on engine 2 start.
Fortunately, in all four events, the starboard area of the aircraft was clear. In three of the events, the start attendant promptly made the crew aware the propeller was spinning and the crew responded by shutting engine 2 down. In the fourth event, as all other tasks were complete, a start clearance was gained, the before start checklist was actioned, and the flight proceeded.

Visual scan by CM2: only control always present

There are multiple opportunities for flight crew to identify the propeller brake status including the shutdown procedure on arrival, the parking checklist, a physical check during the walkaround, the preliminary cockpit preparation procedure and the cockpit configuration, the final cockpit preparation checklist and the HOTEL mode start procedure. However, as can be seen from the events experienced, all of these risk controls are
not always in play.
Crew are reminded that the visual scan by CM2 at HOTEL mode start is thus the key preventative control to capture the propeller brake status. It is the only control that is always present, regardless of engineering intervention after other controls have been completed or with an early HOTEL start to alter cabin temperature. Best practice would suggest CM1 should also visually check the propeller brake status prior to announcing ‘confirmed’ for HOTEL mode start.
If all the aforementioned controls fail, the only barrier to prevent injury or damage to personnel and equipment, is the visual check that the starboard area of the aircraft is clear by both CM2 and the start attendant. A methodical visual check, prior to starting, is thus also critical.

Ammended procedures

A review of the Part B procedures associated with HOTEL mode was conducted and resulted in several changes with the amendment effective April 22nd:

3.19.4 On arrival and shutdown, CM2 is now required to monitor CM1’s actions after parking at the gate until the beacon is selected off and is to confirm that propeller 2 has stopped. This is an alignment with ATR FCOM procedures.
3.5 HOTEL mode may now only be started with both flight crew members on the flight deck. This gives the best opportunity for the propeller brake status to be identified, and, given the criticality of the visual check of the starboard area prior to start, ensures CM2 is present.
3.5.3 Prior to starting HOTEL mode, CM2 is now required to check for the blue ‘PROP BRAKE’ caption on the EWD. Poor illumination of the propeller brake light on the overhead panel prior to start had been highlighted as a threat.

There are no further procedural changes planned, however, this will be reviewed should similar future events occur. Crew are reminded of the diligence required when conducting the current procedures, the need for checklist discipline and the threat of confirmation bias.
Communications will also be sent to ground staff, enforcing the criticality of their visual check of the starboard area prior to them giving a clearance to start HOTEL mode and treating every engine start as ‘live’.
Line maintenance staff will also be reminded of the importance of returning the aircraft configuration to its original state after performing any maintenance activity e.g. a propeller inspection.

Hotel Mode Start events