- Engine:
- 3612 (S/N: NZA1-UP)
- Marine Engine:
- C280-12 (S/N: TSJ1-UP; RDW1-UP)
- 3616 (S/N: ZYD1-UP; 1PD1-UP; RMN1-UP; 1FN1-UP)
- 3612 (S/N: 9RC1-UP; 9FR1-UP; 2NZ1-UP)
- C280-16 (S/N: NKB1-UP; TDX1-UP)
Description of Change: A new air shutoff is used on these engines. The new air shutoff has the following improvements:
- An improved paddle for improved sealing
- An improved bumper for better absorption of impact
- New gasket material for improved sealing
- An increased number of flange bolts in order to improve the clamping force.
Adaptable To: The former 193-4652 Air Shutoff Gp has been cancelled and replaced by the new 317-9554 Air Shutoff Gp. The above engines are now produced with the new air shutoff. The new air shutoff is adaptable to all earlier engines.
The new air shutoff is effective with the serial numbers that are listed in Table 1.
| Effective Serial Numbers |
| S/N:9RC00493-UP |
| S/N:2NZ00176-UP |
| S/N:1PD00551-UP |
| S/N:1FN00152-UP |
| S/N:NZA00111-UP |
| S/N:RMN00113-UP |
| S/N:ZYD00102-UP |
| S/N:RDW00107-UP |
| S/N:TDX00134-UP |
| S/N:TSJ00104-UP |
| S/N:NKB00126-UP |
Note: For consistent operation, a minimum supply pressure to the air shutoff must be above 1100 kPa (160 psi). The maximum allowable supply pressure is 1720 kPa (250 psi).After the new air shutoff is installed, the new air shutoff must be exercised by operation. The new air shutoff must be operated after every 150 hours of service or the air shutoff must be operated weekly.