Did Degraded Engines Down USAF V-22?
Ecce Homo! Loquitur...
Thread Starter
Did Degraded Engines Down USAF V-22?
Shades of the UK Chinook accident? There's a lot of pressure to cancel the Osprey, and an equal pressure inside the USMC to protect it's reputation.
Ares: Did Degraded Engines Down USAF V-22?
USAF officers disagreed over the cause of the first combat loss of a V-22 Osprey tilt-rotor, according to a report in the Fort Worth Star-Telegram, with a senior general ultimately overruling the investigation team and declaring the cause to be pilot error. The April 9 accident killed four people, including the pilot, and injured 16. The full report is here.
A major complicating factor was that the CV-22B wreckage was bombed hours after the accident to prevent sensitive equipment from being removed, and the flight incident recorder was never recovered.
The CV-22B unit had ferried its aircraft into Afghanistan eight days before the accident, which took place on its first operational mission, infiltrating a special operations team into an unprepared site. The report notes that the three-aircraft formation encountered unexpected tailwinds on the approach.
Following a low-visibility approach that the investigators described as "poorly executed" and a rapid rate of descent, the aircraft landed with a 75-knot forward speed. The nosewheel bounced, then collapsed, and the aircraft slid forwards until it struck an irrigation ditch, separating the cockpit from the forward fuselage and causing the aircraft to flip over and break up.
Brig Gen Donald Harvel, president of the board, determined "from the preponderance of the evidence" that the Osprey had experienced power loss on the approach, leading to a high rate of descent and making it impossible to go around. Video of the accident and of strike marks on the ground showed that the proprotor speed was 78-80 per cent of nominal RPM, which could only be caused by substantial power loss.
Engine power had been measured on April 6, but Harvel finds it possible that after four subsequent austere landings, including one where the engine air particle separator (EAPS) failed, "one or both of the mishap aircraft's engines was degraded below acceptable standards". Harvel believes that the accident crew recognized an excessive descent, found a go-around impossible due to lack of power, and attempted a "near perfect roll-on landing".
However, Lt. Gen. Kurt Cichowski, vice commander of Air Force Special Operations Command, the convening authority for the investigation board, ruled that engine power loss could not be considered as a major factor in the accident.
Harvel notes that had the nose gear not collapsed and if the aircraft had not struck the ditch, damage and injuries would have been much less severe. Separate testing by the Navy has shown that the V-22's STOL performance is limited by the nose landing gear, which early trials showed cannot clear a 2-inch bump at more than 25 knots.
Ares: Did Degraded Engines Down USAF V-22?
USAF officers disagreed over the cause of the first combat loss of a V-22 Osprey tilt-rotor, according to a report in the Fort Worth Star-Telegram, with a senior general ultimately overruling the investigation team and declaring the cause to be pilot error. The April 9 accident killed four people, including the pilot, and injured 16. The full report is here.
A major complicating factor was that the CV-22B wreckage was bombed hours after the accident to prevent sensitive equipment from being removed, and the flight incident recorder was never recovered.
The CV-22B unit had ferried its aircraft into Afghanistan eight days before the accident, which took place on its first operational mission, infiltrating a special operations team into an unprepared site. The report notes that the three-aircraft formation encountered unexpected tailwinds on the approach.
Following a low-visibility approach that the investigators described as "poorly executed" and a rapid rate of descent, the aircraft landed with a 75-knot forward speed. The nosewheel bounced, then collapsed, and the aircraft slid forwards until it struck an irrigation ditch, separating the cockpit from the forward fuselage and causing the aircraft to flip over and break up.
Brig Gen Donald Harvel, president of the board, determined "from the preponderance of the evidence" that the Osprey had experienced power loss on the approach, leading to a high rate of descent and making it impossible to go around. Video of the accident and of strike marks on the ground showed that the proprotor speed was 78-80 per cent of nominal RPM, which could only be caused by substantial power loss.
Engine power had been measured on April 6, but Harvel finds it possible that after four subsequent austere landings, including one where the engine air particle separator (EAPS) failed, "one or both of the mishap aircraft's engines was degraded below acceptable standards". Harvel believes that the accident crew recognized an excessive descent, found a go-around impossible due to lack of power, and attempted a "near perfect roll-on landing".
However, Lt. Gen. Kurt Cichowski, vice commander of Air Force Special Operations Command, the convening authority for the investigation board, ruled that engine power loss could not be considered as a major factor in the accident.
Harvel notes that had the nose gear not collapsed and if the aircraft had not struck the ditch, damage and injuries would have been much less severe. Separate testing by the Navy has shown that the V-22's STOL performance is limited by the nose landing gear, which early trials showed cannot clear a 2-inch bump at more than 25 knots.
After reading the report it seems closer to Elmendorf. Tail wind landing, not following procedures, copilot not doing his proper duties, etc.. Add to this that there is no evidence of any engine problems.
The Sultan
The Sultan
Megan
The Hawaii incident has indications of a known issue with the GFE engine. Bell has been flying a barrier engine filter for a year or more with great success demoed in brown out conditions. Time for NAVAIR to get it to the fleet. This may provide the kick.
As to Afghan, they weren't hovering, we're not in brown out so no similarities.
The Sultan
The Hawaii incident has indications of a known issue with the GFE engine. Bell has been flying a barrier engine filter for a year or more with great success demoed in brown out conditions. Time for NAVAIR to get it to the fleet. This may provide the kick.
As to Afghan, they weren't hovering, we're not in brown out so no similarities.
The Sultan
Ecce Homo! Loquitur...
Thread Starter
The Hawaii incident has indications of a known issue with the GFE engine.
"Investigation of a fatal accident in May involving a Bell-Boeing MV-22B Osprey tiltrotor transport points to an undiagnosed failure mode in the Osprey’s trouble-prone propulsion system and has resulted in tight restrictions on restricted visibility landing (RVL) operations. The preliminary report findings—disclosed in documents obtained by Aviation Week—also reopen questions about an April 2010 fatal accident involving a U.S. Air Force CV-22B in Afghanistan. In that case, a senior officer dismissed investigators’ focus on engine problems and put blame on the pilots.
A major modification to fix the Osprey’s perennial problem—damage to engines caused by the dense and high-energy dust cloud the aircraft creates when landing on any loose surface—is under development, but testing will not be completed until late 2017 and the cost and time required to retrofit the fleet is unknown.......
Two U.S. Marines died, and two pilots and 18 other occupants were injured May 17 when an MV-22B crashed while attempting an RVL at Bellows AFS on Oahu, Hawaii...... The likely cause of the power loss, according to the document, was that the engine ingested sand containing reactive minerals—classified as calcium, magnesium, aluminum and silicon (CMAS) compounds—which melted in the combustor and solidified on the fixed first-stage turbine vane. This restricted airflow and reduced surge margin, but indications of these conditions to the aircrew “are not sufficient,” the report says. Throttle movement can trigger a surge with no other warning......
The Navair report identifies three earlier surge events related to reactive sand, one of which—on Aug. 26, 2013, at Creech AFB, Nevada—resulted in a Class A mishap and the loss of the aircraft in a postimpact fire. In addition, surveys of flight operations have found six more “rapid power loss events” in areas where there is known to be reactive sand.
The problem is compounded by lack of essential data. The Rolls-Royce AE1107C has not been tested for its resistance to CMAS ingestion. The problem is different from the engine’s long-running issue: compressor-blade erosion caused by ingested particles, which gradually saps performance until the engine is overhauled........
The newly discovered risk factors in the Hawaii accident parallel known information about the first Osprey combat loss, an Air Force CV-22B that crashed in Afghanistan in April 2010......
Correct, ORAC.
The long-running problem has been gradual temp margin/power loss resulting from erosion of the compressor blades. This newly diagnosed issue (confirmed also as the cause of an aircraft lost near Creech in 2013 - nonfatal, off public land and swept under the rug) affects the turbine and can result in no-warning surge and power loss.
The Afghan aircraft was known to have had an ingestion event shortly before the accident.
The new inlet is a fairly substantial mod and won't finish testing until late '17.
The long-running problem has been gradual temp margin/power loss resulting from erosion of the compressor blades. This newly diagnosed issue (confirmed also as the cause of an aircraft lost near Creech in 2013 - nonfatal, off public land and swept under the rug) affects the turbine and can result in no-warning surge and power loss.
The Afghan aircraft was known to have had an ingestion event shortly before the accident.
The new inlet is a fairly substantial mod and won't finish testing until late '17.
@ORAC: interesting for them to look with a new set of eyes on causal factors. Thanks for the update.
