F-14 Single engine controllability
Glenn A Stegink
I was watching a documentary last night titled "Navy Blues" (or at least
that was what the aussie channel on which it screened called it) - it was
about the aftermath of the tailhook sexual harrasment political feeding
frenzy of 1991.
In this documentary they showed some footage of a (the first?) female
F-14 pilot crashing on approach to a carrier. Apparently her left engine
was stalled on the approach as evidenced by some black smoke it emitted.
The narrator stated "she probably didn't know this". Can this be true?
I was under the impression that a stalling jet engine would be surging
and making an almighty racket which would leave the pilot in no doubt as
to what's going on.
She was waved off, and on the wave off the aircraft continued descending
while yawing/rolling to the left until it ended up alongside and below
the flight deck out of control and rolling rapidly through 90 degrees
bank. The WSO punched out just in time to be shot into the air and
survived, the pilot followed 1/2 a second later and was shot into the sea
and died. This leads to my next question - is the F-14 (with those
widely spaced engines) controllable at approach speeds with full
afterburner on one engine, or is it necessary to modulate power on the
operating engine for a single engine wave-off until the speed comes up?
In other words would the knowledge her left engine was stalled have made
any difference to the technique to be used, or was it simply a matter of
not recognising and correcting the yaw quickly enough.
Glenn
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Ptolomy
Glenn A Stegink <gste...@bigfoot.com> wrote:
>In this documentary they showed some footage of a (the first?) female
>F-14 pilot crashing on approach to a carrier. Apparently her left engine
>was stalled on the approach as evidenced by some black smoke it emitted.
>The narrator stated "she probably didn't know this". Can this be true?
>I was under the impression that a stalling jet engine would be surging
>and making an almighty racket which would leave the pilot in no doubt as
>to what's going on.
I will refrain from commenting on this specific incident, as I am
unfamilliar with all of the facts pertaining to said event.
But, when a jet engine stalls, there may or may not be an audible
indication. There will in most cases be unusual, and typically
noticeable, vibration - but even this is not always the case.
If one were to look at the instruments, RPM would certainly be
dropping, and EGT would be climbing as a result.
However, when a pilot is trying to make a landing, they are usually
fairly absorbed into the task, especially if it is a particularly
difficult landing ( I understand that carrier landings are among the
most challenging ) Therefore, if the pilot was concentrating on the
task at hand, it is conceivable that any (if any) external indication
of a stall could have gone unnoticed. It would, however, not be very
long at all before the pilot would realize that something was not
performing as expected. I have had pilots come back from missions,
and report no problems - that all had operated as normal, and the
engine tracking data say that the engine had experienced a stall at
some point during the flight. Not an entirely common event, but it
does occur from time to time. Hope this helps.
Regards, JCD A&P, F-16 Engine Tech, USAF.
Bill Horne
Glenn A Stegink wrote:
>
> I was watching a documentary last night titled "Navy Blues" (or at least
> that was what the aussie channel on which it screened called it) - it was
> about the aftermath of the tailhook sexual harrasment political feeding
> frenzy of 1991.
>
> F-14 pilot crashing on approach to a carrier. Apparently her left engine
> was stalled on the approach as evidenced by some black smoke it emitted.
> The narrator stated "she probably didn't know this". Can this be true?
> I was under the impression that a stalling jet engine would be surging
> and making an almighty racket which would leave the pilot in no doubt as
> to what's going on.
An engine stall may be noticed by the pilot. They were not unusual for
the
J-57's mounted on the A-3 while on approach. However, an engine may
flameout
without stalling. If the pilot was below speed, and a little late in
recognizing
the flameout, the task of directional control may have become too much
to
manage.
Bill Horne
Burkhard Domke
On Wed, 14 Jan 1998 23:34:49 -0600, Glenn A Stegink
<gste...@bigfoot.com> wrote:
> [...] is the F-14 (with those
>widely spaced engines) controllable at approach speeds with full
>afterburner on one engine, or is it necessary to modulate power on the
>operating engine for a single engine wave-off until the speed comes up?
>In other words would the knowledge her left engine was stalled have made
>any difference to the technique to be used, or was it simply a matter of
>not recognising and correcting the yaw quickly enough.
According to standard operational procedures, military and civil
alike, aircraft must not be operated below OEI (one engine
inoperative) minimum control speed. This is the minimum speed (plus a
margin) needed to provide sufficient aerodynamic forces with the
control surfaces to compensate for an unbalanced yawing moment
developed by an inoperative engine (less thrust, additional
windmilling drag).
I'm not familiar with the specific incident you refer to, but I
suspect a more complex chain of events here. A simple, isolated engine
failure on approach/finals is not catastrophic by instance. In some
cases though, decisive action has to be taken by the pilot within a
few seconds after engine failure to prevent a total loss of control,
especially when near the limits of the flight envelope.
Full afterburner on the remaining engine is not helpful in a low
speed, high alpha situation, as this will build up unbalanced moment
much faster than speed and control forces respectively, unless the
thrust can be properly vectored by means of TVC.
HTH
Burkhard
Jeff Shultz
On Thu, 15 Jan 1998 16:25:47 GMT, Burkhard Domke wrote:
::>I'm not familiar with the specific incident you refer
to, but I
:>suspect a more complex chain of events here. A simple, isolated engine
:>failure on approach/finals is not catastrophic by instance. In some
:>cases though, decisive action has to be taken by the pilot within a
:>few seconds after engine failure to prevent a total loss of control,
:>especially when near the limits of the flight envelope.
It was the Kara Hultgren incident... and the Navy's report
on it basically said, "she screwed up and got into a
situation that she never should have been in."
Jeff Shultz
http://www.netcom.com/~jbshultz
Less than a year left in the Army - and this time I mean it!
John Kunkel
Glenn A Stegink wrote:
>
> I was watching a documentary last night titled "Navy Blues" (or at least
> that was what the aussie channel on which it screened called it) - it was
> about the aftermath of the tailhook sexual harrasment political feeding
> frenzy of 1991.
>
> In this documentary they showed some footage of a (the first?) female
> F-14 pilot crashing on approach to a carrier. Apparently her left engine
> was stalled on the approach as evidenced by some black smoke it emitted.
> The narrator stated "she probably didn't know this". Can this be true?
> I was under the impression that a stalling jet engine would be surging
> and making an almighty racket which would leave the pilot in no doubt as
> to what's going on.
>
> while yawing/rolling to the left until it ended up alongside and below
> the flight deck out of control and rolling rapidly through 90 degrees
> bank. The WSO punched out just in time to be shot into the air and
> survived, the pilot followed 1/2 a second later and was shot into the sea
> widely spaced engines) controllable at approach speeds with full
> afterburner on one engine, or is it necessary to modulate power on the
> operating engine for a single engine wave-off until the speed comes up?
> In other words would the knowledge her left engine was stalled have made
> any difference to the technique to be used, or was it simply a matter of
> not recognising and correcting the yaw quickly enough.
The P&W TF30 series engine has been plagued with compressor stalls
since day one. The stalling problem is exacerbated by large changes
in the attitude of the AC which affects the smooth flow of air into
the inlet ducts.
In the incident mentioned above it is believed the pilot made a rather
steep turn to the left to correct her alignment with the deck while
simultaneously making a major throttle movement to increase power to
both engines. The interrupted flow of air caused by the left turn and
the throttle increase probably caused the left engine to stall while
the right engine responded to the throttle increase and pulled the AC
to the left. The loss of the engine at relatively low airspeed and
altitude was a major factor in the loss of the AC but some have argued
that a more skilled pilot could have recovered from the yaw or wouldn't
have been out of position to start with.
John
Jarmo Lindberg
According to mishap investigation report:
Aircrew factor - Pilot (Lt. Kara Hultgreen) attempt to salvage overshooting
approach led to reduced engine stall margin, contributing to left eng comp
stall.
Aircrew factor - Pilot failed to execute proper single engine wave off
procedures.
Aircrew factor - Pilot failed to inform Radar Intercept Officer (Lt. Klemish)
of single engine emergency
Material factor - Left engine directional control valve stuck in bleeds
closed position.
Aircrew factor - MP (Mishap Pilot) failed to make timely decision to eject.
MP lost situational awareness, failed to scan AoA (Angle of Attack), allowed
pitch attitude to slowly increase and exceed maximum controllable AoA of 20
units.
The causal factors of this mishap and injury are a result of overcontrol,
external distraction, cognitive saturation, channelized attention, wear
debris, complacency and problem not foreseeable.
From 'Bogeys and Bandits' by Robert Gandt, p. 117
--
Jarmo Lindberg
Fighter Squadron 21: http://www.mil.fi/ftrsqn21/
Fighter Tactics Academy: http://www.sci.fi/~fta/welcome.htm
ch1...@earthlink.net
Hey Jarmo,
I'm not sure what combination of residual clustering is available to the
RIO (flight only or engines too?) but I remember reading or maybe it was
'seeing', on a Wing's episode, that the backseater helped the pilot
maintain his visual instrument scan and offset any tendency to vertigous
behavior through excessive heads-up/down, focus in/out translations.
Maybe things change as the backseater locks himself up for the trap?
Also, was the pilot using DLC and would the new digital FCS comining
online or the F-110's higher residual thrust/faster spool up have helped
any at all? Are the A's getting a full-HUD (airspeed pitch-yaw etc.)
capabilityl like the B/D?
With Thanks.
John Carrier
>The narrator stated "she probably didn't know this". Can this be true?
>I was under the impression that a stalling jet engine would be surging
>and making an almighty racket which would leave the pilot in no doubt as
>to what's going on.
Not much racket under certain flight conditions. Probably heard a "pop" and
that's about all. Don't know if stall warning system was installed in her
particular jet.
>This leads to my next question - is the F-14 (with those
>widely spaced engines) controllable at approach speeds with full
>afterburner on one engine, or is it necessary to modulate power on the
>operating engine for a single engine wave-off until the speed comes up?
>In other words would the knowledge her left engine was stalled have made
>any difference to the technique to be used, or was it simply a matter of
>not recognising and correcting the yaw quickly enough.
F-14's approach is at 15 units angle of attack. F-14A has insufficient
control authority at 15 units with one in A/B, the other out. This problem
normally occurred on Cat shots, an engine would go and you'd have only one.
Procedure was to limit AOA to 14 or less and use rudder/stick to maintain
level flight (actually you want a little wing down into good engine, but
wings level is good enough). A little more complicated in the approach, as
you're already at 15 units, albeit much lighter gross weight. Single engine
waveoff in military power (not A/B) is not a problem normally.
R/ John (former fighter pilot)
JamesK7766
a report of the accident was on america online aviation library
the pilots name was kara haultgreen i dont know if the spelling is right.if i
remember right the enigne flamed out commpressor stall
and she was late in getting the correct control corrections.both
ejected the rio got out she was a second or two late and hit the water.also the
engine had a stuck relief valve.this with the fact that she over shot the
approach and yawed it around produced the compressor stall and flame out.If i
remember correctly?
Gun One
: some have argued
: that a more skilled pilot could have recovered from the yaw or wouldn't
: have been out of position to start with.
I'll argue the other side .. the CO of her squadron took all of his pilots
over to the simulator and put them thru the same (as near as he could
reconstruct the event at the time) scenario. Only one pilot out of the
14 or 15 in the squadron could save the aircraft, and that was the CO
hisself.
An engine loss in-close at the boat requires absolute split-second
responses, both in recognition and correction, and it's especially
critical in the Tomcat because of the 12 feet or so between the
thrust lines of the engines. Four-tenths of a second was the
difference between life and death here .. the back-seater ejected
0.4 sec before the front, and he made it okay.
As far as being out of position to start with... the secret of a
good pass is a good start, and that's really true, but all approaches
are a constant series of corrections. The best pilots see the
trends quicker and can make smaller corrections, but the difference
between "best" and "good" is truly a fine line.
-gun one]
Gun One
"Jeff Shultz" <jbsh...@ix.netcom.com> said:
> It was the Kara Hultgren incident... and the Navy's report
> on it basically said, "she screwed up and got into a
> situation that she never should have been in."
I believe the final findings were, in fact, "pilot error," with a
fairly long list of contributory factors. I'm not sure I know what
you're referring to when you mention the situation she "never
should have been in." Can you clarify?
-gun one
Gun One
"John Carrier" <j...@netdoor.com> said (among other things);
> F-14A has insufficient control authority at 15 units with one
> in A/B, the other out.
My well-worn F-14A NATOPs, dated 1978, sez it IS controllable
in A/B, but adds the "Warning" that application of rudder must
be made before application of afterburner or an out-of-control
situation may result.
Wouldn't surprise me that time and experience have changed
the wording, esp after Kara's accident. Or maybe we're saying
the same thing after all ... if you're in burner when one engine
goes, you either get out of burner or get out of the airplane.
-gun one
Jeff Shultz
On Fri, 16 Jan 1998 16:00:47 GMT, Gun One wrote:
That when she suffered a compressor stall, she got into an
unrecoverable AOA....
Jeff Shultz
On Fri, 16 Jan 1998 15:55:41 GMT, Gun One wrote:
:>I'll argue the other side .. the CO of her squadron took all of his pilots
:>over to the simulator and put them thru the same (as near as he could
:>reconstruct the event at the time) scenario. Only one pilot out of the
:>14 or 15 in the squadron could save the aircraft, and that was the CO
:>hisself.
Interesting... I'd never heard that one.
Jarmo Lindberg
ch1...@earthlink.net wrote:
> Hey Jarmo,
>
> I'm not sure what combination of residual clustering is available to the
> RIO (flight only or engines too?) but I remember reading or maybe it was
> 'seeing', on a Wing's episode, that the backseater helped the pilot
> maintain his visual instrument scan and offset any tendency to vertigous
> behavior through excessive heads-up/down, focus in/out translations.
>
> Maybe things change as the backseater locks himself up for the trap?
>
> Also, was the pilot using DLC and would the new digital FCS comining
> online or the F-110's higher residual thrust/faster spool up have helped
> any at all? Are the A's getting a full-HUD (airspeed pitch-yaw etc.)
> capabilityl like the B/D?
>
> With Thanks.
I assume that the crew workload has been co-ordinated to some extent but since I'm
just an air force weenie I can't say :-) (even though I fly a Navy jet)
Uri Blumenthal
Jeff Shultz wrote:
> :>......Only one pilot out of the 14 or 15 in the squadron
> :>could save the aircraft, and that was the CO hisself.
>
> Interesting... I'd never heard that one.
I did - but scenario they played began when the situation was
"fully unfolded". The commission report meant (as I understand
it) that she shouldn't have gotten into that situation in the
first place, and that's what they're faulting her for (not for
her inability to recover AFTER all the bad things happened).
--
Regards,
Uri
-=-=-==-=-=-
<Disclaimer> COLT...The original point and click interface!
Gun One
ch1...@earthlink.net wrote:
> I'm not sure what combination of residual clustering is available to the
> RIO (flight only or engines too?) but I remember reading or maybe it was
> 'seeing', on a Wing's episode, that the backseater helped the pilot
> maintain his visual instrument scan and offset any tendency to vertigous
> behavior through excessive heads-up/down, focus in/out translations.
>
One instrument which might have saved this trajedy from happening that
the back seater didn't have was (is?) an AOA gage.
-gun one
Gun One
In article <34be2e45...@news.cs.tu-berlin.de>, domk...@sp.zrz.tu-berlin.de (Burkhard Domke) writes:
|>
|> According to standard operational procedures, military and civil
|> alike, aircraft must not be operated below OEI (one engine
|> inoperative) minimum control speed.
Horse pucky. The F-14 has no such "operational procedure," nor does any
Navy fighter I ever flew.
|> Full afterburner on the remaining engine is not helpful in a low
|> speed, high alpha situation, as this will build up unbalanced moment
|> much faster than speed and control forces respectively, unless the
|> thrust can be properly vectored by means of TVC.
On the contrary, full a/b is sometimes all that pulls you out. Of course
it builds up an unbalanced moment, but proper and timely application of
rudder prevents the type of accident that Kara fell victim to. TVC??
C'mon.
-gun one
Burkhard Domke
On Thu, 22 Jan 1998 18:01:33 GMT, pie...@pat.mdc.com (Gun One) wrote:
>In article <34be2e45...@news.cs.tu-berlin.de>, domk...@sp.zrz.tu-berlin.de (Burkhard Domke) writes:
>|>
>|> According to standard operational procedures, military and civil
>|> alike, aircraft must not be operated below OEI (one engine
>|> inoperative) minimum control speed.
>
>Horse pucky. The F-14 has no such "operational procedure," nor does any
>Navy fighter I ever flew.
Sorry, my dictionary isn't conclusive about "horse pucky".
As I have no access to the according MIL-SPEC at the moment, I can't
comment on that precisely. Nevertheless, I'm sure as cancer that there
_is_ a VMC or equivalent in the MIL certification requirements as well
as in the F-14 aircraft operating manual.
(for Minimum Control Speed term go to bottom of message)
>|> Full afterburner on the remaining engine is not helpful in a low
>|> speed, high alpha situation, as this will build up unbalanced moment
>|> much faster than speed and control forces respectively, unless the
>|> thrust can be properly vectored by means of TVC.
>
>On the contrary, full a/b is sometimes all that pulls you out. Of course
>it builds up an unbalanced moment, but proper and timely application of
>rudder prevents the type of accident that Kara fell victim to.
Absolutely, unless speed was allowed to bleed below VMC... ;-)
> TVC?? C'mon.
Well, ...TVC was added rather preemptively, with the FSU
clever-buggers in mind...Nevertheless, smartly integrated into the
control laws, TVC may have prevented exactly what Mrs. Hultgren fell
victim to.
regards,
Burkhard
Berlin, Germany
FAR25 Airworthiness Standards - Transport Category Airplanes, see:
<http://www.faa.gov/avr/AFS/FARS/far_idx.htm>
---cite---
Sec. 25.149 Minimum control speed.
(a) In establishing the minimum control speeds required by this
section,
the method used to simulate critical engine failure must represent
the most
critical mode of powerplant failure with respect to controllability
expected
in service.
(b) VMC is the calibrated airspeed at which, when the critical
engine is
suddenly made inoperative, it is possible to maintain control of the
airplane
with that engine still inoperative and maintain straight flight with
an angle
of bank of not more than 5 degrees.
(c) VMC may not exceed 1.2 VS with--
(1) Maximum available takeoff power or thrust on the engines;
(2) The most unfavorable center of gravity;
(3) The airplane trimmed for takeoff;
(4) The maximum sea level takeoff weight (or any lesser weight
necessary to
show VMC);
(5) The airplane in the most critical takeoff configuration
existing along
the flight path after the airplane becomes airborne, except with the
landing
gear retracted;
(6) The airplane airborne and the ground effect negligible; and
(7) If applicable, the propeller of the inoperative engine--
(i) Windmilling;
(ii) In the most probable position for the specific design of the
propeller
control; or
(iii) Feathered, if the airplane has an automatic feathering
device
acceptable for showing compliance with the climb requirements of
Sec. 25.121.
(d) The rudder forces required to maintain control at VMC may not
exceed
150 pounds nor may it be necessary to reduce power or thrust of the
operative
engines. During recovery, the airplane may not assume any dangerous
attitude
or require exceptional piloting skill, alertness, or strength to
prevent a
heading change of more than 20 degrees.
(e) VMCG, the minimum control speed on the ground, is the
calibrated
airspeed during the takeoff run at which, when the critical engine
is
suddenly made inoperative, it is possible to maintain control of the
airplane
using the rudder control alone (without the use of nosewheel
steering), as
limited by 150 pounds of force, and the lateral control to the
extent of
keeping the wings level to enable the takeoff to be safely continued
using
normal piloting skill. In the determination of VMCG, assuming that
the path
of the airplane accelerating with all engines operating is along the
centerline of the runway, its path from the point at which the
critical
engine is made inoperative to the point at which recovery to a
direction
parallel to the centerline is completed may not deviate more than 30
feet
laterally from the centerline at any point. VMCG must be established
with--
(1) The airplane in each takeoff configuration or, at the option
of the
applicant, in the most critical takeoff configuration;
(2) Maximum available takeoff power or thrust on the operating
engines;
(3) The most unfavorable center of gravity;
(4) The airplane trimmed for takeoff; and
(5) The most unfavorable weight in the range of takeoff weights.
(f) VMCL, the minimum control speed during approach and landing
with all
engines operating, is the calibrated airspeed at which, when the
critical
engine is suddenly made inoperative, it is possible to maintain
control of
the airplane with that engine still inoperative, and maintain
straight flight
with an angle of bank of not more than 5 degrees. VMCL must be
established
with--
(1) The airplane in the most critical configuration (or, at the
option of
the applicant, each configuration) for approach and landing with all
engines
operating;
(2) The most unfavorable center of gravity;
(3) The airplane trimmed for approach with all engines operating;
(4) The most favorable weight, or, at the option of the applicant,
as a
function of weight;
(5) For propeller airplanes, the propeller of the inoperative
engine in the
position it achieves without pilot action, assuming the engine fails
while at
the power or thrust necessary to maintain a three degree approach
path angle;
and
(6) Go-around power or thrust setting on the operating engine(s).
(g) For airplanes with three or more engines, VMCL-2, the minimum
control
speed during approach and landing with one critical engine
inoperative, is
the calibrated airspeed at which, when a second critical engine is
suddenly
made inoperative, it is possible to maintain control of the airplane
with
both engines still inoperative, and maintain straight flight with an
angle of
bank of not more than 5 degrees. VMCL-2 must be established with--
(1) The airplane in the most critical configuration (or, at the
option of
the applicant, each configuration) for approach and landing with one
critical
engine inoperative;
(2) The most unfavorable center of gravity;
(3) The airplane trimmed for approach with one critical engine
inoperative;
(4) The most unfavorable weight, or, at the option of the
applicant, as a
function of weight;
(5) For propeller airplanes, the propeller of the more critical
inoperative
engine in the position it achieves without pilot action, assuming
the engine
fails while at the power or thrust necessary to maintain a three
degree
approach path angle, and the propeller of the other inoperative
engine
feathered;
(6) The power or thrust on the operating engine(s) necessary to
maintain an
approach path angle of three degrees when one critical engine is
inoperative;
and
(7) The power or thrust on the operating engine(s) rapidly
changed,
immediately after the second critical engine is made inoperative,
from the
power or thrust prescribed in paragraph (g)(6) of this section to--
(i) Minimum power or thrust; and
(ii) Go-around power or thrust setting.
(h) In demonstrations of VMCL and VMCL-2--
(1) The rudder force may not exceed 150 pounds;
(2) The airplane may not exhibit hazardous flight characteristics
or
require exceptional piloting skill, alertness, or strength;
(3) Lateral control must be sufficient to roll the airplane, from
an
initial condition of steady flight, through an angle of 20 degrees
in the
direction necessary to initiate a turn away from the inoperative
engine(s),
in not more than 5 seconds; and
(4) For propeller airplanes, hazardous flight characteristics must
not be
exhibited due to any propeller position achieved when the engine
fails or
during any likely subsequent movements of the engine or propeller
controls.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt.
25-42, 43 FR
2321, Jan. 16, 1978; Amdt. 25-72, 55 FR 29774, July 20, 1990; 55 FR
37607,
Sept. 12, 1990; Amdt. 25-84, 60 FR 30749, June 9, 1995]
Gun One
In article <6a8vri$8o8$2...@hecate.umd.edu>, na...@Glue.umd.edu (David Hyde) writes:
|>
|> Maybe something's lost in translation here - but at the ship, if you're
|> getting the proper endspeed off the cat and flying onspeed AW, then you're
|> above Vmc, since Vmc is one of the criteria used to select cat mins and
|> onspeed AOA in development. 'Operational procedure? Not stated as such,
|> but in all practicality it is. Out of the landing pattern? Yoyo. What
|> would the call be? "Knock it off, I'm below Vmc" - what happened to 'call
|> ballistic'?
|>
|> Dave '>1 engine, of course' Hyde
Maybe times change. In the F-4 and F-8, you point the nose straight up, pick
your spot, and roll/push/yaw the nose down behind the baddie. Airspeed below
Vmc? Lotsa times. Airspeed ZERO?? Once in awhile, whatever it took. Had flames
coming out of your intake??! Been there, done that. Called "Knock it off, I'm
below Vmc"?? Never ... let the other guy figure that out for himself. ;-)
-gun one