A Saab 340 was started with a strap still attached to its left propeller following a series of missed checks, an ATSB investigation has found.
On 19 November 2024, the Regional Express aircraft was prepared for departure from Melbourne Airport. After the pilots started the engines, a passenger told the flight attendant they had seen a strap restraining the left propeller before it began to spin.
The flight attendant advised the pilots, who shut down the engines. The propeller strap was then found attached to the propeller, with the pins that connect it to the engine cowling broken on start-up.
ATSB Director Transport Safety Dr Stuart Godley said the strap was inadvertently left on the propeller after being missed in a series of pre-flight checks.
“Actions from multiple individuals contributed to the development of this incident, with the first officer, the captain and the ground handler, who was a trainee, all required to check for the presence of the strap prior to engine start,” Dr Godley said.
The ATSB final report notes the final external walkaround check of the aircraft required the first officer to remove the propeller strap from the propeller, before rotating the propeller to a required position.
However, the first officer inadvertently left the propeller strap attached, instead only disconnecting and removing the strap extension, which connects the propeller strap to the aircraft stairs to prevent them from being retracted while the strap is in place.
“The first officer completed their walkaround and boarded the aircraft, entering the flight deck with just the propeller strap extension in their hands, but without the strap itself,” Dr Godley said.
Once the first officer was in the flight deck, the ground handler assigned to the dispatch, who was a trainee, did not detect the propeller strap from their position at the nose of the aircraft, and provided the crew with a signal to start the engine.
Meanwhile, the pilots conducted the engine start checklist, which included a requirement for the captain to check that the left engine was clear. The captain also did not detect the propeller strap and proceeded to start the engine.
“The absence of a strap extension allowed the aircraft stairs to be retracted, and removed a visual cue, reducing the likelihood that either the captain or the trainee ground handler would detect the propeller strap,” Dr Godley noted.
While the individual actions of multiple personnel contributed to the incident, the ATSB’s investigation identified safety issues in the training and procedures for ground handling personnel.
“This incident highlights the critical safety role performed by ground handling personnel, who are often the last line of defence in ensuring commercial aircraft are prepared safely for departure,” Dr Godley said.
“Operators should seek to ensure that ground handling procedures and training are designed to effectively support the ability to check for safety critical items.”
In addition to the missed check by the ground handler trainee, the ATSB found the ground handler’s supervisor had left the apron before the trainee had completed the dispatch.
It also found Regional Express procedures did not define the roles and expectations of trainers during practical ground handling training.
In response, Regional Express has taken actions aimed at providing greater assurance that ground handling staff and flight crews are adequately checking for propeller straps during aircraft preparation.
“While it is valuable for new personnel to demonstrate their capability prior to being deemed competent, this incident highlights the potential for on-the-job training to introduce safety risks, and why it is critical that supervisors maintain oversight of trainees in safety critical contexts,” Dr Godley said.
“Operators should ensure they clearly articulate the roles and expectations of personnel supervising practical training for safety critical tasks.”
The incident was the second investigated by the ATSB involving a strap being inadvertently left on a Saab 340 propeller. In November 2022, a Link Airways Saab 340 was taking off from Canberra when a propeller strap was thrown free of the blade and embedded in the cabin wall. In addition, cowling pins penetrated the cabin, with one striking a passenger, resulting in a minor bruising injury.
“Both of these incidents highlight that ground handling procedures and training should be effectively designed to support the ability to check for safety critical items,” Dr Godley concluded.
“They should also remind operators to assess the conspicuity of items such as straps, tags and chocks which need to be detected and removed prior to flight, and how ground handling personnel are taught to look for them.”
Read the final report: Aircraft preparation event involving Saab 340B, VH-OLL, at Melbourne Airport, Victoria, on 19 November 2024