Possible Clues:

• Occasion for engineers to talk of salvation
• Take the engineer's tip and make a significant saving
• Do you need a helping hand in the scree?
• Can the engineer help making a cannon with this?
• Soldiers' signal recovery
• Army group's signal to get back
• Regret having swallowed key, seeking release
• "Baywatch" staple
• Save for this, it's the engineer's sign to come in
• Engineers prompt Conrad's ?deliverance