Two cases of driver death caused by airbag rupture

Abstract

Objective

This article reports two accidents caused by defective Takata airbags ruptured, which led to the deaths of the drivers. This is the first public report on the deaths caused by Takata airbags in China.

Methods

Determine the relationship between the driver death and airbag rupture through autopsy indings and vehicle inspection.

Results

Due to defects in the design of Takata’s inflator, moist air was permitted to slowly enter the inflator, resulting the PSAN slowly degraded physically. The damaged propellant burned more rapidly than intended and overpressurized the inflator’s steel housing, causing fragmentation and flying debris at high speed, killing or injuring vehicle occupants.

Conclusions

To date, there are still tens of millions of defective Takata airbags that have not been recalled for repair, posing safety risks. This article suggests taking preventive measures to avoid the occurrence of similar accidents.

Keywords:

• Inflator
• PSAN
• Takata
• propellant
• recall

Introduction

A driver-side airbag is designed to provide effective crash protection for drivers. According to statistics, a driver’s airbag can reduce the driver death rate in frontal collisions by 16% to 29% (Braver et al. 2003). However, an airbag may also cause injury to a driver, such as eye injury, head and face injury, cervical spine injury, heart injury, thoracic aorta rupture, skin burns, etc. (Cunningham et al. 2000; Wallis and Greaves 2002; Thekkudan et al. 2012; Inamasu and Kato 2018; Marta et al. 2020; Plodr et al. 2021; Subedi et al. 2021; Alshehri et al. 2022). As of December 2020, the defective airbags produced by Takata Company in Japan have caused more than 400 injuries and 18 deaths in the United States (NHTSA 2020b), including facial or neck cuts, facial fractures, loss of vision and tooth fractures (McCrary et al. 2016; NHTSA 2017). This led to the largest and most complex automobile recall in American history, involving 67 million defective airbags from 19 American automobile manufacturers. In addition, defective airbags caused the death of a driver with head and face penetration injuries in the Kingdom of Bahrain and the death of a driver with neck penetration injuries in the United Arab Emirates (Albalooshi et al. 2021; Fouda and Almaged 2022). Due to frequent deaths, Takata airbags are called “death airbags”. Although automobile enterprises around the world have recalled relevant models many times, “death airbags” still threaten many car owners.

This article reports two accidents caused by defective Takata airbags ruptured, which led to the death of the drivers, analyses the injury process and proposes preventive measures. This is the first public report on the deaths caused by Takata airbags in China.

Methods

Cases presentation

Case 1: As shown in Figure 1, a slight collision occurred on the left front of a black car in Guangzhou in April 2022, causing the driver to be injured. The driver fell to the ground after walking out of the car and died after being sent to the hospital.

Figure 1. The left front of the black car collision.

Case 2: As shown in Figure 2, the front of a blue car collided in Guangzhou in September 2022, causing the driver to die at the scene.

Figure 2. The front of the blue car collision.

Autopsy findings

Case 1: The driver was a 35-year-old male whose body was subjected to a complete forensic autopsy. This autopsy produced the following findings. As shown in Figure 3, there was a circular contusion wound (3.1 cm × 2.7 cm) on the right upper chest, reaching the chest. There was a fracture of the right second anterior rib and fifth posterior rib, bleeding in the muscle around the fourth and fifth posterior ribs, and the right pleural hemorrhage was 1500 mL. There was a penetrating wound (5.0 cm × 3.5 cm × 3.0 cm) in the upper lobe of the right lung. There was subcutaneous bleeding on the right back and bleeding in the corresponding muscle, and a cylindrical metal object was extracted from the muscle of the right back (metal A), as shown in Figure 4. The cause of death of the driver was lung rupture combined with traumatic hemorrhagic shock.

Figure 3. Round laceration wound on the right chest.

Figure 4. Cylindrical metal extracted from the right back (metal a).

Case 2: The driver was a 45-year-old male whose body was subjected to a complete forensic autopsy. This autopsy produced the following findings. As shown in Figure 5, there was a round laceration wound (3.2 cm × 1.8 cm) in the left chest, reaching the chest. There was a comminuted fracture of the second and third anterior ribs and the second posterior rib of the left side, and the left pleural hemorrhage was 1000 mL. There was a penetrating wound (3.2 cm × 1.8 cm) in the lower lobe of the left lung and a contusion wound (3.2 cm × 1.8 cm) in the posterior wall of the left chest. A cylindrical metal object was extracted from the muscle on the left back (metal M), as shown in Figure 6. The cause of death of the driver was lung rupture combined with traumatic hemorrhagic shock.

Figure 5. Round laceration wound on the left chest.

Figure 6. Cylindrical metal extracted from the left back (metal M).

Vehicle inspection

Case 1: The vehicle was manufactured by Guangqi Honda Co., Ltd. in China, model called CITY, and the manufacturing date was January 2010,which VIN is LHGGM2555********.The driver-side airbag burst and there were many blood stains on the surface of the airbag. After the airbag was removed, a cylindrical metal object was embedded in the middle of the steering wheel (metal B), as shown in Figure 7. The label paper of the driver-side airbag inflator is printed with the words "TAKATA-PETRI AG" .

Figure 7. A cylindrical metal object (metal B) was embedded in the middle of the steering wheel.

Case 2: The vehicle was manufactured by Guangqi Honda Co., Ltd. in China, model called CITY, and the manufacturing date was March 2006,which VIN is LHGGD8545********.The driver-side airbag burst and there were many blood stains on the surface of the airbag. A cylindrical metal object was found near the accelerator (metal N), as shown in Figure 8. The label paper of the driver-side airbag inflator is printed with the words "TAKATA SACHSEN".

Figure 8. A cylindrical metal object (metal N) was found near the accelerator.

Before the accident, neither vehicle went to the original factory to recall and replace the airbag. The residual airbag and inflator information was identified, and it shows that the inflators of both vehicles were produced by the Takata Company of Japan.

Results

Identification of integrated separation of metal object traces

As shown in Figure 9, the broken ends of metal A and metal B are spliced together, and their material, color, internal and external diameter, cylinder wall thickness, broken end shape, and separation edge concave convex characteristics are consistent and formed by the same separation. The overall structure of the two is shown to be the inflator canister of the airbag. Similarly, as shown in Figure 10, the broken ends of metal M and metal N are spliced together to form the inflator canister of the airbag.

Figure 9. Splicing of broken ends of metal A and metal B.

Figure 10. Splicing of broken ends of metal M and metal N.

Analysis of injury process

The core component of an airbag is the inflator, which is located at the bottom of the airbag. The shell of the inflator is a metal canister, often made of steel, which can contain explosive chemical propellant. The gas generated by the propellant fills the airbag through an air hole on the canister, expanding the airbag. Driver-side airbags are commonly housed in the steering wheel. In an airbag inflator that functions normally, the chemical propellant begins to burn after activation by an electrical spark initiated when vehicle sensors detect a collision. When functioning properly, the chemical propellant burns in a fast and controlled manner, quickly emitting a gas through vents in the canister out into the airbag, which inflates to cushion the vehicle occupant.

Takata was the only major airbag inflator manufacturer to have used phase stabilized ammonium nitrate (PSAN) as its chemical propellant. However, due to defects in the design of Takata’s inflator, moist air was permitted to slowly enter the inflator. When the inflator was exposed to high temperature and humidity for a long time, the PSAN slowly degraded physically due to temperature cycling. During subsequent airbag deployment in a crash, the damaged propellant burned more rapidly than intended and overpressurized the inflator’s steel housing, causing fragmentation and flying debris at high speed, killing or injuring vehicle occupants (NHTSA 2020a, 2020b).

In the two accidents in this article, the driver-side airbag inflator separated as a whole with the six air vents on the canister wall as the separation points, forming metal fragments and flying out at high speed, hitting the driver’s chest.

Discussion

The accidents reported in this article occurred in Guangzhou, located in South China. The area has a high temperature and humidity and is a high-risk area for Takata inflator explosion accidents. Since 2014, the State Administration for Market Regulation of the People’s Republic of China has carried out defect investigations on the rupture of Takata airbag inflators and issued Takata airbag safety tips (SAMR 2014). SAMR is still issuing the recall announcement of Takata airbag in January 2023 (SAMR 2023).As of 2020, of the 67 million defective Takata airbags that need to be recalled in the United States, about 50 million have been recalled, over 11 million remain unaccounted (NHTSA 2020b). China has about the same number of cars as the United States, and tens of millions of defective Takata airbags are estimated to remain unrecalled, posing safety concerns. To avoid the occurrence of similar accidents, the following preventive measures are suggested:

• Divide risk areas. According to the Takata inflator explosion conditions, areas are divided into three risk levels, namely, high-risk areas, medium-risk areas and low-risk areas. For vehicles in high-risk areas, it is necessary to check whether a vehicle is within the Takata airbag recall scope during annual vehicle inspection or purchase of vehicle insurance.

• Mobilize car owners to actively cooperate with the recall. It is suggested to use words such as “emergency recall” and “mandatory recall” to describe the urgency of the recall and words such as “explosion” and “fatal” to describe the reasons for the recall. At the same time, it is recommended to increase the exposure of Takata airbag injuries to attract the attention of car owners.

• Strengthen the supervision of defective product recalls. Strengthen the collection and analysis of defect information, defect investigation and supervision of recall implementation, carry out timely defect investigation on vehicles that may have defects, supervise and urge enterprises to fulfill their recall obligations, and ensure the personal and property safety of consumers.

• Step up investigation of airbag explosion cases. No matter what brand of airbag explosion cases, a three-way comprehensive investigation is carried out by automotive experts, trace experts and forensic experts to clarify the effectiveness and limitations of airbag protection for passengers, so as to timely discover defective airbags and avoid causing more casualties.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author, upon request.

Additional information

Funding

We acknowledge the financial support from National Natural Science Foundation of China (No. 81971802).