Date: 201310
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Light: Dusk
Aircraft: Citation II S2/Bravo (C550)
Operator: Air Carrier
Operating under: Part 91
Mission: Other Reposition
Flight phase: Parked
Aircraft component: Nose Gear Door
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Lead Technician
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Human factors: Training / Qualification; Situational Awareness; Time Pressure; Distraction; Confusion; Communication Breakdown
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Detector: Person Maintenance; Person Flight Crew
When detected: In-flight
Result: Flight Crew Returned To Departure Airport; General Maintenance Action; General Flight Cancelled / Delayed
Contributing factors: Incorrect / Not Installed / Unavailable Part; Procedure; Human Factors; Aircraft
Primary problem: Human Factors

Narrative: Mechanic helper was directed to gain access to Nose Landing Gear (NLG) Shimmy Damper through the nose baggage floor to facilitate check fluid level. Helper also had removed hardware for aft nose gear door hinges uncommanded. Before work commenced on the Shimmy Damper; a significant Skydrol leak was discovered in the aft baggage area. Mechanic on Duty informed Dispatch that due to the leak; flight scheduled for departure would be cancelled. Dispatcher became verbally abusive to Mechanic demanding the aircraft be repaired immediately. Leak was located in the Aft Bay overhead; and during effecting repair of the leak; both the Mechanic and helper suffered from significant exposure to Skydrol [fluid]. Access to a shower in the hangar was blocked due to items being stored in the shower area; and that area being used as an office by another hangar tenant. Suffering severe skin burning pain; helper left to decontaminate at his residence. Nose baggage bay was closed up following fluid level check of Shimmy Damper and the plane launched; pilots returned after takeoff after hearing unusual noise from the nose gear area. Scheduled flight was then cancelled. Post flight inspection revealed nose gear doors were not secured to aft hinges. There was no damage to the aircraft. Factors include: 1) Time pressures. 2) Physical pain. 3) State of mind; due to verbal abuse [by Dispatcher]. 4) Poor communication. 5) Training.

Callback: Reporter stated the whole event started when he received a call on his day off that help was needed on a Cessna Citation 550 aircraft. The thrust reversers would deploy; but the throttles would not spool up. While troubleshooting that issue in the aft bay compartment; also known as the 'Hell Hole'; he and a Mechanic helper noticed an overhead 'B' nut leaking Skydrol hydraulic fluid. They did relieve the Hydraulic reservoir head pressure; but a substantial amount of Skydrol fluid had poured on their chests; as they had to lay on their backs to also replace an O-ring that decided to leak on the Hydraulic filter relief valve housing. Even with eye goggles on; they had some fluid in their eyes and fluid running down their arms and shoulders. They had to throw their upper body clothes away due to the amount of saturation from the Skydrol. Reporter stated the pilots wanted to take the aircraft; even with the throttle problems and said they would close-up the nose gear doors. The flight was a repositioning flight under Part 91; no passengers. The flight returned due to noises from the NLG area because the NLG doors did not close after takeoff. The Mechanic Helper had disconnected the control rods (tubes) earlier when he was checking the NLG Shimmy Damper fluid level; without telling him (reporter). The aircraft was 32 years old.



Synopsis: A Lead Aircraft Maintenance Technician (AMT) describes how significant exposure to himself and a Mechanic's helper from leaking Skydrol hydraulic fluid in the Aft Bay compartment of a Cessna Citation 550; along with several other factors; contributed to a later air turn back of the aircraft.