Gulfstream G200 (IAI 1126 Galaxy)
Maintenance Airframe; Maintenance Powerplant
Situational Awareness; Communication Breakdown; Troubleshooting
Aircraft Equipment Problem Critical
Aircraft Aircraft Damaged; Flight Crew Diverted; Flight Crew Landed in Emergency Condition; General Maintenance Action; General Flight Cancelled / Delayed
Chart Or Publication; Manuals; Procedure; Aircraft
A Gulfstream G-200 arrived with the following logbook write-up discrepancy: Left engine anti-ice light EICAS message comes on with power above 95-percent and engine anti-ice is not selected. Anti-Ice System checks properly on ground. In short the engine is getting [sending] bleed pressure to the [Anti-Ice] System; even though the switch is 'Off;' which makes sense because it is a fail-safe system which fails in the 'Open' position through a spring load. Since it was receiving the correct electrical signals when troubleshooting; it was determined that the valve failed 'Open'. When the technicians checked the system on the ground; the troubleshooting checks found no discrepancies electrically; but they did duplicate the Anti-Ice 'On' at the high power run-up pad. The Pressure Regulating and Shut-Off Valve (PRSOV) was thought to be the culprit; because of the message showing up only at high engine speeds/high pressure and was electrically operating correctly. When the left-hand engine upper and lower cowls were removed from the aircraft so they could gain access to the valve; they [cowls] were inspected visually as part of a general Serviceability Check. At that time a small crack was found on the left-hand upper engine cowl; this was located in the forward section of the cowl directly adjacent to the anti-ice valve. There was no discoloration on the cowl which would have pointed to a bleed leak. It was thought to be a stress crack at the time. Since no replacement cowl was available; and the aircraft was due into inspection at Gulfstream's [Repair Station]; the most time and cost economical solution was to ferry the aircraft to the [Repair Station] and repair the cowl there during the inspection. Gulfstream issued a letter of 'No Objection to Ferry' the aircraft to the [Repair Station]. The crack was to be speed-taped over to provide a smooth contour. This was accomplished after the anti-ice valve was installed; operationally [checked] and leak checked. The aircraft departed on the ferry flight five days later and had a bleed air leak which damaged the EEC and the engine experienced an in-flight shutdown. The aircraft returned to the local area; but landed at an adjacent airport after approximately thirty minutes of flight time.In regards to the installation of the left-hand anti-ice valve and Operational/Leak Checks: the pressure sense line; which tee's off the lower duct; is not disturbed when changing the anti-ice valve. There is no Leak Check called out on either the [Anti-Ice] Valve Replacement [Job] Card or the Functional Check Card. The Leak Check at idle speeds was complied with by the Technician; but it appears at an idle setting that the engine produces such a low pressure of air that a small leak would go unnoticed. An Engineering Technical Change Request; [was submitted] to make changes to the Aircraft Maintenance Manual (AMM) and job card to reflect the requirement to perform a leak check of the [anti-ice] valve/entire system affected. This Change Request has already been requested through the aircraft's Manufacturer. Leak checks should be at an increased power setting to ensure a leak; if present; can be identified. At idle; these leaks may not be present. Technicians should inspect an entire system/area when performing maintenance in that area to ensure its integrity. The Vendor [a Contract Maintenance Provider] in this incident has already made policy changes to that effect. The left-hand engine anti-ice pressure sense line B-nut was loose; causing hot bleed air to leak. This caused damage to the left-hand engine and an in-flight shutdown. [I am the] Maintenance Manager.
I worked on a Gulfstream G200. The pilot squawk stated Left engine anti-ice light EICAS message comes on with power above 95% and engine anti-ice is not selected. Anti-Ice System checks properly on ground. This item was placed on MEL until it was flown in for maintenance where we turned on to the work. We researched the Anti-Ice System and troubleshot down to the anti-ice valve. During the removal of the upper cowling; we found a crack/delamination in the cowling. We forwarded the information to the aircraft Manufacturer's Technical Operations and Engineering. We repositioned the right-hand and left-hand anti-ice valves to see if the problem would move. To test the system; we taxied the aircraft to a run-up area to run the engines at power. While advancing power levers we; immediately received a right-hand engine anti-ice EICAS message; confirming that the squawk had moved from the left-hand [engine] side to the right-hand [engine] side. We taxied the aircraft back to the FBO and repositioned [the anti-ice] valves to their original positions and performed a Leak Check on the right-hand side. We advised Gulfstream Technical Operations and Engineering of the bad anti-ice valve; and [they] ordered a new valve. The next day; I returned and worked on installing the anti-ice valve. After I installed the valve; we performed a Leak Check at idle. We then taxied the aircraft to the run-up area and performed Functional Checks. All checks were good. Regarding the delamination in the cowling; Engineering responded with a disposition to fly straight into maintenance. We complied with the disposition instructions and the aircraft was released for [a ferry] flight. Five days later; flight crew departed for Gulfstream's [Repair Station]. While climbing out of 12;500 FT; an EICAS message appeared stating left-hand FADEC faulty; followed by an Interstage Turbine Temperature (ITT) rise and a slight N2 spike. The engine then auto-shutdown in flight and the crew declared an emergency landing in [a local adjacent airport] without incident. Upon further investigation; we found a loose B-nut on the pressure sense line going from the anti-ice ducting to a pressure transmitter. We at NO point touched that line. During our Leak Check; we checked the anti-ice valve we [had] removed and replaced. No leaks were noted.
A Maintenance Manager for an Air Operator and two contracted Line Maintenance Technicians report on a Gulfstream G-200 aircraft that landed in an emergency condition after a bleed air leak had damaged the EEC causing an auto-shutdown of the left engine. Lack of a Leak Check callout on the Anti-Ice Valve Replacement Job Card and Functional Check Card were also noted.