The Strategic Airlifters: C-5 C-17 C-141

Flying Safety, Jan-Feb, 2002 by Maj David L. Kral

Introduction

Airlifters, we're doing well, but we can do better. FY01 was not the best year for Strategic Airlift, but not the worst either. Safety incidents cycle a little over time and last year we were slightly up on our rates. Minimizing rates is not the real goal; saving assets, to include personnel and aircraft, is our goal. Complacency is the biggest area in which we can continue to improve. Last year, complacency manifested itself in a lack of personal discipline and attention-to-detail, which led to the majority of the following mishaps. As I review the class A, B and C mishaps that occurred in FY 01, four unofficial categories jump out at me. Engines (18), Landing gear/brakes (9), Structural (12), and a smattering of other areas I'll call Miscellaneous (6). Let me begin with engines.

Engine Mishaps

The engines on large aircraft are expensive items. In fact, of the ten class B mishaps in the strategic community last year, nine were engine-related.

The C-5 Galaxy community had three mishaps.

* The first was discovered during preflight and consisted of damage to a single second-stage fan blade. It appeared the damage happened while the engine was static.

* The second was due to a bird strike on a touch-and-go. The crew successfully shut down the engine and landed uneventfully.

* The third engine mishap was due to FOD. During a ground maintenance engine run, FOD was ingested into the engine, causing significant damage to several fan blades and the honeycomb structure around them.

The C-17 Globemaster III led the way (not a good thing, in this case) with ten engine mishaps, and seven--repeat, seven-of them were due to FOD. There were three non-POD reports.

* A computer malfunction led to improper engine response on run-up for a static takeoff. Additional damage to the engine occurred during maintenance troubleshooting after the jet was returned to parking.

* The second event happened when a Permanent Magnet Alternator (PMA) was contaminated. The PMA stopped powering both channels of the Electronic Engine Control (EEC). As advertised, when both channels failed, the engine reverted to "Safe" mode, with minimum fuel flow. Subsequent, intermittent PMA power led to other malfunctions that required an engine change.

* The third incident is still under investigation. Initial reports indicate there was an oil filter 4 Warning Annunciator Panel (WAP) indication, and then the engine rolled back on its own at FL 350. Talk to your local safety office for a copy of the final message when it is available.

The other seven C-17 engine mishaps resulted from FOD.

* Four were suspected bird strikes, one ingested a stone, and another incident involving ice ingestion damaged three of the four engines, requiring a total of 50 fan blades to be replaced. This crew flew almost six hours to their next station before the damage was discovered. And finally, a crew unknowingly ingested FOD into two engines while backing over an unpaved surface to prepare for a combat offload. This crew took off again and flew the remaining five hours of their local.

The C-141 Starlifter had five engine mishaps, and all of them were in the Class B mishap dollar-value category.

* The first was due to accepted risk. A portion of the turbine failed on climbout, causing an engine failure. This type of failure has happened before, but through engineering analysis and safety review, the USAF has determined that these failures are an acceptable risk. The crew safely returned to base.

* The second mishap occurred during an engine run. Two engines were being run at 1.8 EPR to facilitate troubleshooting when one of the engines catastrophically failed.

* The other three mishaps were due to FOD. All FOD damage was found by maintenance and the damage was bad enough for the engines to be replaced. In each case, the aircrew that flew the flight prior to the damage discovery had no indication anything was wrong.

Engine failures due to mechanical problems will continue to be a factor we have to live with. While we continue to work with manufacturers to identify and improve reliability, sometimes things just break. Where we can help ourselves is by using proper mission planning techniques to avoid areas where there is a high potential for bird strikes.

If you've done the proper planning and you get to a low-level or transition field and notice a significant number of birds, go elsewhere or "incomplete" your training. An extra flight to accomplish your requirements is more beneficial to the USAF than losing an engine or, even worse, an entire aircraft and crew.

FOD: We all learn about FOD from Day One in our respective career fields. Be vigilant, follow the ASRR and Giant report information, and use common sense. If a situation looks bad, come up with another option or clean it up prior to operating in the area.

Landing Gear/Brake Mishaps

Now we'll get into the C-5's favorite area. Although landing gear/brake mishaps seem to be a constant for the C-5, the C-17 has taken over the lead in pure numbers for this category.