Bell 407
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Just a Theory
Spoke to a pilot who was in one of the first 407 tailrotor seperation accidents.He managed to land the beast in one peace.
This is his explenation:
"I was flying along by myself doing about 126kts indicated when all of a sudden the tail yawed to the left. I entered a auto and landed safely.My explenation is that the leading edge on the t/r blade delaminated causing enough friction to brake the shaft.The blades then flaped excessively and cut off the tail with the remaining momentum."
He's theory did sound convincing.
Could this be true
Spoke to a pilot who was in one of the first 407 tailrotor seperation accidents.He managed to land the beast in one peace.
This is his explenation:
"I was flying along by myself doing about 126kts indicated when all of a sudden the tail yawed to the left. I entered a auto and landed safely.My explenation is that the leading edge on the t/r blade delaminated causing enough friction to brake the shaft.The blades then flaped excessively and cut off the tail with the remaining momentum."
He's theory did sound convincing.
Could this be true
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I'm thinking that such a failure should also have caused a torque spike, which should have been recorded in the FADEC memory? After all, there would have to be a lot of power added to break the shaft, the governing system would have added power to maintain RRPM as that blade failed?
just throwing out thoughts.
just throwing out thoughts.
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Bell 407
I've been told PHI has grounded its 407 fleet.
My source told me a fault with the No.3 turbine is suspected following recent crashes and that, with Rolls Royce support, PHI is replacing it throughout its entire fleet of about 35 aircraft.
Fact? Or false rumour?
My source told me a fault with the No.3 turbine is suspected following recent crashes and that, with Rolls Royce support, PHI is replacing it throughout its entire fleet of about 35 aircraft.
Fact? Or false rumour?
Unfortunate timing perhaps ... a new press release has come in..
The Bell 407 fleet has surpassed the 1,000,000 flight hours mark. The major milestone was reached in November. One million hours, that equals a little more than 114 years or just less than 11 and ½ decades or around 41,667 days. No matter what terms you use to describe it, 1 million hours is a lot of time.
A lot of it about ... MD just annouced 500,000 NOTAR fleet hours...
The Bell 407 fleet has surpassed the 1,000,000 flight hours mark. The major milestone was reached in November. One million hours, that equals a little more than 114 years or just less than 11 and ½ decades or around 41,667 days. No matter what terms you use to describe it, 1 million hours is a lot of time.
A lot of it about ... MD just annouced 500,000 NOTAR fleet hours...
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From what I hear, there is a bulletin out on the turbine blades, some were defective and recalled, but more were found defective when they were inspected. Rolls-Royce may have a big problem here. The PHI fleet has been grounded indefinitely, it seems, and are being covered by 206s for the time being. It might behoove other operators to do the same thing. People are dying in 407s, and not inspecting them could be found to be negligence if lawsuits were to be filed, leading to very large jury awards. Rolls-Royce could have lots of liability here. Just speculation, you understand.
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As Gomer says the PHI 407 fleet remains grounded due to suspected engine issues with the C47. According to sources, PHI will not "unground" the fleet until suspect engines have been replaced.
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STRANGE - From the ASB CEB–A–72–6048 issued on 2nd OCTOBER (and revised on 6th) and further covered by Bell ASB 407-03-61 (issued 21nd NOVEMBER):
"Recently, an incident was experienced in which a 4th–stage turbine wheel (23066744) was found to have an over blended, thin trailing edge. Although blending is a common procedure for turbine wheels, in this particular case the turbine wheel blade trailing edge was blended beyond print requirements. All Rolls-Royce Model 250–C30, –C40 and –C47 series 4th–stage turbine wheels (23066744), S/N X504345 and earlier require a one-time inspection to verify that the blades do not have a thin trailing edge."
"For 4th–stage turbine wheels (23066744, S/N HX76702 to HX76755): Compliance Code 2. Turbine wheels which have over 1000 hours must be inspected within the next 150 hours. Turbine wheels which have less than 1000 hours must be inspected within the next 300 hours or at 1000 hours, whichever comes first."
Inspection is with a simple go-no gauge and can be done installed. Failure requires removal of wheel and fitment of new blades.
NOW.... OPTIONS
a) this ASB could be just a coincidence and there is a further problem with 3rd stage (though no ASB or FAA EAD issued as yet to my knowledge)
or
b) 10 weeks after the ASB is issued, an operator with many affected 407s with >1000 hours on their turbine wheels have used up the 150 hours and not having yet done the checks are thus grounded
or
c) 10 weeks on the inspection failure rate is outstripping the overhaul shops' ability to replace the blades
or
d) things have moved on, the problem is (or is seen as) more serious and PHI have judged the inspection is not sufficient
"Recently, an incident was experienced in which a 4th–stage turbine wheel (23066744) was found to have an over blended, thin trailing edge. Although blending is a common procedure for turbine wheels, in this particular case the turbine wheel blade trailing edge was blended beyond print requirements. All Rolls-Royce Model 250–C30, –C40 and –C47 series 4th–stage turbine wheels (23066744), S/N X504345 and earlier require a one-time inspection to verify that the blades do not have a thin trailing edge."
"For 4th–stage turbine wheels (23066744, S/N HX76702 to HX76755): Compliance Code 2. Turbine wheels which have over 1000 hours must be inspected within the next 150 hours. Turbine wheels which have less than 1000 hours must be inspected within the next 300 hours or at 1000 hours, whichever comes first."
Inspection is with a simple go-no gauge and can be done installed. Failure requires removal of wheel and fitment of new blades.
NOW.... OPTIONS
a) this ASB could be just a coincidence and there is a further problem with 3rd stage (though no ASB or FAA EAD issued as yet to my knowledge)
or
b) 10 weeks after the ASB is issued, an operator with many affected 407s with >1000 hours on their turbine wheels have used up the 150 hours and not having yet done the checks are thus grounded
or
c) 10 weeks on the inspection failure rate is outstripping the overhaul shops' ability to replace the blades
or
d) things have moved on, the problem is (or is seen as) more serious and PHI have judged the inspection is not sufficient
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Zalt
Problem suspected as per Flying Lawyer with No.3 wheel, not No.4 wheel.
Your (d) is correct and PHI will replace suspect engines as well as replace all wheels on a continuous basis at less than 1000 hours total time.
Hip
Problem suspected as per Flying Lawyer with No.3 wheel, not No.4 wheel.
Your (d) is correct and PHI will replace suspect engines as well as replace all wheels on a continuous basis at less than 1000 hours total time.
Hip
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Steve,
If you - or any of our other Model 250-C47B/47M operators - have any concerns regarding the current engine investigation, as described in the Bell Service Letter posted below (Bell ASB 407-03-73), I would strongly encourage you to contact the customer support team here in Indy ([email protected] or phone: 317 230 2720).
Since the investigation is still on-going, it's not appropriate for me to provide further comment on the root cause (as much as I might want to), but I will say that the current focus of the investigation is on the -C47B/407 rather than the -C47M/MD600N, due to differences in the engine running speed.
There is a substantial effort being undertaken by the team here in Indy (in cooperation with Bell and the NTSB) to fully understand and address this issue, and further information will be released through the proper channels as soon as it is known.
Fly safe,
t/shaft
-----
Information Letter 407-03-73
December 14, 2003
TO: All Owners/Operators of Bell 407 series Helicopters
SUBJECT: Information on Model 407
There have been 2 incidents in the Texas gulf coast area involving the Model 407 since November of this year. The preliminary investigation suggests that they may be engine related. The investigation by the NTSB is on going at this time.
Both Bell and Rolls-Royce have formed a joint action team to ensure that the combined assets of both companies are focused on the most rapid resolution of the situation. The engine components have been returned to Rolls Royce under the authority of the NTSB investigation. Important information resulting from the investigation will be distributed rapidly to all the Model 407 operators and maintainers as it becomes available.
Currently there are over 560 Model 407 Rolls-Royce powered helicopters in over 80 different countries around the world. This fleet has accumulated over 1,400,000 flight hours since the introduction in 1996.
Bell Helicopter and Rolls-Royce are committed to the rapid resolution of these events and our desire to keep you well informed.
Any media inquiries regarding these incidents may be directed to Carl Harris in the Bell Helicopter Textron office (phone: 817-280-2783, email: [email protected] ).
Customer inquires may be directed to Jack Denham, Director Product Support (phone: 817 280-3344, email: [email protected] ).
In case of questions about the involvement of the engine:
Please direct any media inquiries regarding this incident to Maria Weber in the Corporate Communications office (phone: 317-230-6662, email: [email protected] ).
Please direct any customer inquiries regarding this incident to Gary Souza in the Model 250 support team (phone: 317-230-3987, email: [email protected] ).
If you - or any of our other Model 250-C47B/47M operators - have any concerns regarding the current engine investigation, as described in the Bell Service Letter posted below (Bell ASB 407-03-73), I would strongly encourage you to contact the customer support team here in Indy ([email protected] or phone: 317 230 2720).
Since the investigation is still on-going, it's not appropriate for me to provide further comment on the root cause (as much as I might want to), but I will say that the current focus of the investigation is on the -C47B/407 rather than the -C47M/MD600N, due to differences in the engine running speed.
There is a substantial effort being undertaken by the team here in Indy (in cooperation with Bell and the NTSB) to fully understand and address this issue, and further information will be released through the proper channels as soon as it is known.
Fly safe,
t/shaft
-----
Information Letter 407-03-73
December 14, 2003
TO: All Owners/Operators of Bell 407 series Helicopters
SUBJECT: Information on Model 407
There have been 2 incidents in the Texas gulf coast area involving the Model 407 since November of this year. The preliminary investigation suggests that they may be engine related. The investigation by the NTSB is on going at this time.
Both Bell and Rolls-Royce have formed a joint action team to ensure that the combined assets of both companies are focused on the most rapid resolution of the situation. The engine components have been returned to Rolls Royce under the authority of the NTSB investigation. Important information resulting from the investigation will be distributed rapidly to all the Model 407 operators and maintainers as it becomes available.
Currently there are over 560 Model 407 Rolls-Royce powered helicopters in over 80 different countries around the world. This fleet has accumulated over 1,400,000 flight hours since the introduction in 1996.
Bell Helicopter and Rolls-Royce are committed to the rapid resolution of these events and our desire to keep you well informed.
Any media inquiries regarding these incidents may be directed to Carl Harris in the Bell Helicopter Textron office (phone: 817-280-2783, email: [email protected] ).
Customer inquires may be directed to Jack Denham, Director Product Support (phone: 817 280-3344, email: [email protected] ).
In case of questions about the involvement of the engine:
Please direct any media inquiries regarding this incident to Maria Weber in the Corporate Communications office (phone: 317-230-6662, email: [email protected] ).
Please direct any customer inquiries regarding this incident to Gary Souza in the Model 250 support team (phone: 317-230-3987, email: [email protected] ).
Last edited by turboshaft; 18th Dec 2003 at 20:32.
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A very interesting item in the BHT IL is that there have been '2 incidents in the Texas gulf coast area involving the Model 407 since November of this year'.
There are no relavent entries in the NTSB accident database.
This either suggests these were truely more minor incidents (and not related to 'people dying in 407s' as speculated above) or as discussed in past posts, that the US system is supressing events that other countries would class as accidents.
It would be REALLY useful if anyone of those people close enough to have confirmed the PHI groundings / wheel changes could actually say what happen in these 2 incidents.
Meanwhile, a trivial point - how come the fleet hours have gone from passing 1 million in November to 1.4 million now?
EDIT: After looking through past threads, the ditching of N405PH just after take off from a rig nine miles south of Marsh Island (reported on 16 Nov) is probably one. The absence of this accident from the NTSB database is rather worrying.
There are no relavent entries in the NTSB accident database.
This either suggests these were truely more minor incidents (and not related to 'people dying in 407s' as speculated above) or as discussed in past posts, that the US system is supressing events that other countries would class as accidents.
It would be REALLY useful if anyone of those people close enough to have confirmed the PHI groundings / wheel changes could actually say what happen in these 2 incidents.
Meanwhile, a trivial point - how come the fleet hours have gone from passing 1 million in November to 1.4 million now?
EDIT: After looking through past threads, the ditching of N405PH just after take off from a rig nine miles south of Marsh Island (reported on 16 Nov) is probably one. The absence of this accident from the NTSB database is rather worrying.
Last edited by zalt; 19th Dec 2003 at 01:25.
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Zalt
N405PH was a ditching after take off.
It is not in the NTSB accident database because it was not classified as an "accident" but as an "incident".
No significant damage occurred to the aircraft as a result of the ditching and significant damage (in the opinion of the NTSB investigator assigned) is one of the criteria used to determine whether it is an accident or incident.
LE
N405PH was a ditching after take off.
It is not in the NTSB accident database because it was not classified as an "accident" but as an "incident".
No significant damage occurred to the aircraft as a result of the ditching and significant damage (in the opinion of the NTSB investigator assigned) is one of the criteria used to determine whether it is an accident or incident.
LE
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Accidents aren't listed in the NTSB database until a preliminary report is issued. Apparently the NTSB is still investigating the 407 accidents. There have been at least 2 fatal 407 accidents, neither of which is on the NTSB site, but which have been reported on the FAA preliminary accident site. The FAA reports accidents as they are reported to it, and the information is often sketchy, and sometimes incorrect. The NTSB only issues a report after a probable cause is determined, or when it's a major airline accident, it may release information while the investigation is still ongoing. It's not unusual for accidents not to be listed on the NTSB site for some weeks if a probable cause is not obvious. From the FAA descriptions, the causes of the 407 crashes probably weren't completely self-evident.
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B 407 Fennestron??
Hi All,
I found this while doing a bit of surfing, sounds interesting!!
(quote)
"Although Bell won't unveil an all-new helicopter model, Redenbaugh says he will announce a plan for developing new and improved models at the Helicopter Association International Heli-Expo trade show Sunday.
He declined to discuss specifics, but sources within Bell say engineers are working on three projects that could lead to improved aircraft within a couple of years.
A tail-rotor shroud, known as a fenestron, is being designed and will be tested on a Bell 407, the company's bestselling helicopter. Used for years by other manufacturers, the shroud produces a quieter aircraft and reduces the risk of someone being maimed by the tail rotor"
I found this while doing a bit of surfing, sounds interesting!!
(quote)
"Although Bell won't unveil an all-new helicopter model, Redenbaugh says he will announce a plan for developing new and improved models at the Helicopter Association International Heli-Expo trade show Sunday.
He declined to discuss specifics, but sources within Bell say engineers are working on three projects that could lead to improved aircraft within a couple of years.
A tail-rotor shroud, known as a fenestron, is being designed and will be tested on a Bell 407, the company's bestselling helicopter. Used for years by other manufacturers, the shroud produces a quieter aircraft and reduces the risk of someone being maimed by the tail rotor"
A fenestron type tail rotor is not new to Bell, they dabbled about ten years ago with a 'ring tail' on the 400 [a pre-427 twin]. It was minimalist and probably did little more than mark and guard the outer tail rotor. They dropped it and the 400.
Bell did produce some pictures of a new project using a 'proper' fenestron at HAI - potentially a 206 replacement. It was described as a Gazelle lookalike and that was a fair description.
Bell did produce some pictures of a new project using a 'proper' fenestron at HAI - potentially a 206 replacement. It was described as a Gazelle lookalike and that was a fair description.
