A simple decision.
I was Dash-2 to an AH-1W Super Cobra, and we were tasked with a night-into-day escort of two MV-22s with 40 Marines onboard into a hasty landing zone (LZ). The Marines were part of a raid package searching a cluster of compounds well away from any friendly forward-operating base (FOB), combat outpost (COP) or patrol base (PB). This mission was different because we were tasked with taking four Marines from the ground-combat element (GCE) to serve as an aerial-reaction force (ARF). If personnel or vehicles, commonly known as "squirters," were spotted fleeing the objective area, the Huey would land and drop off the ARF to interdict.
I had a junior copilot in the right seat, an extremely experienced crew chief manning the left side with the GAU-21 (.50 caliber machine gun), and a junior crew chief manning the right side with the GAU-17/A (7.62mm mini-gun). We arrived on-station, completed a sensor scan of the compounds, and the MV-22s conducted the insert without a problem. Our section remained in the overhead after the insert to provide over-watch of the GCE as they entered the compounds and established security. With the ground situation under control and no evident squirters, the GCE asked us to drop off the four Marines next to one of the compounds, so they could rejoin the raid force.
As a utility helicopter, the UH-1Y Huey is routinely tasked with a variety of missions. We felt we had seen them all and were well-prepared for operating in Helmand Province, Afghanistan.
Landing an aircraft near its maximum gross weight in a potential brownout zone, under low-light-level conditions and with a junior copilot is not ideal. However, enough time had elapsed that the sun was now peeking above the horizon, and the aircraft was 300-pounds lighter on fuel. I felt more at ease with the task at hand. The joint-terminal-attack controller (JTAC) requested we insert the ARF adjacent to a compound the GCE had secured, not the insert LZ.
The first zone selected was a mix of decaying poppy plants and sparsely planted wheat adjacent to the compound. I briefed the crew that we would land on the wheat to help reduce some of the brownout. We spiraled down from our holding altitude and made a low-level, straight-in approach to the zone. As the aircraft decelerated below 40 knots, I engaged the hover-aid graphic. At 25 feet, the crew chief stated, "Signature at the tail"--meaning a dust was cloud building.
THE ROTOR WASH KICKED UP ROOTS and debris from the decaying poppy plants, obscuring the ground. As I called, "Waving off," I could hear the clumps of roots bounce off the windscreen and fuselage. I instantly pulled the collective to 100-percent torque, aligned the "pipper" on the horizon, and ensured the "lollipop" on the hover-aid graphic was at the 12 o'clock position. The copilot did exactly what he was supposed to do, calling out "Two positive rates of climb," "Airspeed off the peg," and "Pipper on the horizon." After a couple tense seconds, the aircraft climbed out of the dust. The crew collectively breathed a sigh of relief.
For the second zone, I briefed the crew that we'd make an attempt at a portion of the field that had more vegetation but was farther away from the compound and friendlies. Despite the denser vegetation, the brownout conditions were the same. After waving off for the second time, I decided to insert the four Marines into the LZ used by the MV-22s. The downside to this zone was the distance away from the main body of the GCE. The four Marines would have to cover 150 meters of open terrain to rejoin the friendly elements established in the compounds.
We set-up for another low-level, straight-in approach to the zone. The brownout was bad but manageable. After touching down, the inside of the cabin was covered in wheat chaff. I thought nothing of it at the time and conducted a reduced visibility takeoff out of the zone. As I called, "Visual" with the lead aircraft, I heard the distinct tone of the warning, caution and alert (WCA) system. My first instinct was an overtorque due to the high power required to depart the zone. To my surprise, the WCA was for CBOX TEMP HI. I quickly pulled up the systems 1 page on the multi-function display (MFD) to diagnose the problem. In the UH-1Y, the oil cooler is driven by a hydraulically-driven fan powered by either the hyd 1 or hyd 2 systems. Without the oil-cooler, the combining gearbox and transmission-oil temperatures will rapidly rise, and the aircraft will become unflyable within two-and-a-half minutes. If the primary system failed, the aircraft would have displayed the PRI OIL COOLER FAIL WCA. After looking at the systems 1 and 2 pages, it appeared that the oil cooler was functioning, but the combining-gearbox-oil temperatures continued to rise at about one degree per second.
The senior crew chief said debris from the landing probably clogged the oil cooler, preventing airflow. I quickly decided to land at the LZ we just left, and asked the lead aircraft to coordinate with the JTAC to provide security. As I turned toward final, the thought of waving off was not an option. In the 10 seconds since the WCA illuminated, the oil temperature had climbed well above the NATOPS limit and continued to rise.
A waveoff would have further delayed getting on deck and could have jeopardized the integrity of the combining gearbox. We landed in the zone without a problem and immediately shut down the aircraft. The crew chiefs opened the oil-cooler panel and saw a two-inch pillow of wheat chaff clogging the oil cooler. They immediately began to clear the obstruction.
The four Marines we dropped off had posted security to isolate the compounds to the southwest. So far no one was hurt. We had identified the problem and expected a quick fix. However, the issue complicating our situation was that lead aircraft had only 10 minutes until they hit bingo-fuel state.
If the lead aircraft had to return to base (RTB) for fuel, it would be at least an hour before they'd be back on-station. We had just landed an aircraft in an open field, 40 miles from the nearest friendly position, and were sure that some unwanted attention was on the way. The crew chiefs quickly cleared the obstruction, and all systems looked good. By this time the oil temperature had cooled to its normal operating range. We departed the zone as lead called bingo, and we headed for the airfield.
As we climbed to join with lead, I noticed the combining-gearbox-oil temperatures start to rise again, but at a much slower pace than before. I notified lead of the problem and circled over the landing zone. Could we make the 20-minute flight to the nearest friendly FOB, COP, or PB with an LZ? Compounding the problem was our near-bingo fuel state. I had a choice between risking the 20-minute flight or landing at an LZ where we had 44 Marines that could provide security. The downside to landing in the LZ would be the massive maintenance recovery effort required, and the unwanted attention it would draw from the insurgents. The last choice I wanted was to get halfway and have to conduct another precautionary-emergency landing (PEL) away from any support, leaving the four of us to fend for ourselves.
After about 30 seconds of monitoring the oil temperature, I decided to head to the airfield. I pulled 65-percent torque en route, yielding 110 knots. A higher power setting would have given a maximum cruise airspeed of 125 knots but would have exacerbated the rise in oil temperatures. I wanted to hold the lower power setting and accept the lower airspeed.
All four of us watched the gauge during the flight home, calling out every degree rise in temperature. Lead was miles ahead of us but still in radio contact. I asked him to coordinate with the airfield and declare an emergency for us. In what seemed like the longest 20 minutes of my life, I wondered if I had made the right call. We crossed the threshold of the airfield as temperatures again reached the NATOPS limits. Our postflight found more wheat chaff inside the compartment. It had slowly made its way on top of the oil cooler, obstructing air flow.
We were now behind friendly lines. We cleaned the oil-cooler compartment, completed a functional ground turn, and continued supporting our assigned missions for the day.
Looking back, I had made the right decision and a maintenance-recovery effort had been avoided. However, during the 20-minute flight, I wasn't so sure. The lesson learned is that a relatively simple decision in CONUS becomes complex in a combat environment. NATOPS does not spell out how to handle every possible aircraft emergency. Aircraft commanders must rely on experience, and more importantly, sound judgment when making a decision.
CAPT. SAFINSKI FLIES WITH HLMA-469.
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|Title Annotation:||ORM corner; UH-1Y Huey helicopter landing|
|Date:||Jan 1, 2013|
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