The concern related to a seat harness which had been incorrectly installed on a Boeing 737 and the cabin crew member not informing an engineer to have it corrected.
The reporter expressed a safety concern related to a seat harness which was installed incorrectly on a Boeing 737 they recently flew on. The cabin crew member was alerted to the incorrect installation, but advised the passenger that it would probably be ok and no engineer was called to fix the issue. The reporter closed the seat belt with a twist to align the buckles and the flight continued.
Reporter comment: This is not the first time I have detected an incorrectly fitted seat harness but on the previous occasion, an engineer was summoned to correct the problem, before the flight proceeded.
Due to the confidential nature of this REPCON, an internal investigation into this specific occurrence was not able to be carried out. A review of historical information relating to the seatbelt fitted to the Boeing B737 aircraft and current controls was conducted.
Current controls:
Equipment
- Seatbelt manufacturer provided confirmation that the belt twisting does not impact the airworthiness of the seatbelts as it retains its minimum load without any problems nor does it affect form, fit and function of the seatbelt. The twisting is considered a passenger comfort issue only.
- We have fitted a grommet to the buckles of the seatbelts which has reduced the instances of twisting however; on occasion these are removed by passengers.
Engineering
- Regular inspection of seatbelts is carried out as per the documented Aircraft Maintenance Program with a work instruction provided by the manufacturer for restoration of the webbing to its original orientation.
- Further preventative action of replacing all buckles is currently in progress which will help to reduce the twisting.
Cabin
- The aircrew procedures provide clear direction regarding the reporting requirements for equipment discrepancies.
- The cabin crew procedures details the mechanism by which cabin crew report defects to flight crew.
- Cabin crew training includes modules on the cabin crew responsibilities relating to reporting of aircraft defects to the Captain.
Actions:
- A review of Cabin Safety & Quality Line Surveillance results indicates NIL negative trends in relation to the reporting of defects.
Preventative action
Guidance will be provided to cabin crew to ensure standardised action and appropriate messaging is provided to passengers in cases where a twisted seatbelt is identified.
CASA has reviewed the REPCON and agrees with the operator’s comment from an airworthiness perspective, with the exception of the included comment provided by the manufacturer.
It is agreed that the ability of the belt to retain its minimum load carrying capability is not affect by twisting. However, twisting is more than a "passenger comfort issue". Design standards specify a minimum width for belt webbing, which is based on the allowable pressures to be borne by the occupant's skeletal structure during an impact. Allowing the belt to be twisted means that up to half the webbing width is not available thereby increasing the pressures on the occupant’s hips during an emergency landing with a potential increase in occupant injury.
However this matter has been raised previously with the operator by CASA. Due to the ongoing nature of this issue, CASA intends to target this specific area of continuing airworthiness in forthcoming audits, and to include seat belts fitted to all Boeing 737 aircraft operated by the operator.