View Full Version : Can an aircraft limit be broken for SAR?
25th Jun 2004, 19:32
It was reported the other day that the crew of a RN SAR helo elected to fly above VNE in order to reach the scene of a rescue quicker and therefore have more fuel/time on scene to effect the rescue. Surely VNE is VNE or does the RN allow limits to be broken for lifesaving missions?
Moreover apparently having done the job and got the non critical casualty back to base they then refuelled and flew a now potentially unserviceable aircraft again to take him to the local hospital.
Not wanting to start a witch hunt but does this happen often?
25th Jun 2004, 20:12
I am not military, but deal with SAR on a reglar basis.
Given that they people who fly these missions are the most experienced aircrew in their field, and probably know their aircraft as well as their engineers do, I would say it's judgement call that only they can make, and in doing so they take into account all the factors available to them at the time.
This would not of course, include the judgemental inclusion of hindsight to which you allude to in referring to the casualty as "non critical".
Witch hunt my arse! :rolleyes:
25th Jun 2004, 21:00
I've had to ask a pilot to break Vmax on a couple of occasions. It's not something we take lightly but we genuinely thought the cas was about to peg out.
One died anyway and the other walked out of the hospital less than 24 hrs later without giving his name. Something in the music industry allegedly. Make your own conclusions.
25th Jun 2004, 21:30
Anybody who busts Vne is a suicidal idiot!!!! Other than mortal combat I can see of NO scenario whereby you could justify exceeding that particular airframe parameter.
Ever seen the picture of the Vulcan that exceeded it? Leading edge peeled off a treat!!
It means exactly what it says on the tin!! But then the Air Farce is full of two-winged idiots who think they know better than the manufacturers eh!!
I was unforunate enough to be sat behind one who took my Herc outside the flight envelope at 250'. Scared that apple tree in the orchard far*less we did!! Provided a spectacular display for the M5 though!!
I would imagine a frame that has been deliberately flown above Vne would be destined for a scrapyard! I certainly wouldn't like to fly in it would you??
No pilot or engineer ever knows the frame as well as the manufacturer. It is the manufacturer who sets Vne!!
25th Jun 2004, 21:56
Interested in your comment:
But then the Air Farce is full of two-winged idiots who think they know better than the manufacturers eh!!
When the thread starts:
It was reported the other day that the crew of a RN SAR helo elected to fly above VNE
25th Jun 2004, 22:05
Well done, I wondered how long it would take someone to spot that. I am not changing it cos I have had 2 very bad evenings!!
England was one and the lovely Vanessa of Big Brother is two!!
BLW Skylark 4
25th Jun 2004, 22:32
Not in the same league, but I remember once being in a bar room discussion with several gliding instructors when the hypothetical question arose, suppose you 'lost' it in cloud or the like, is it better to exceed G-Limits or VNE?
Without fail, all the wise ones said respect VNE and pull that G. The airframe tolerances are usually higher for G limits than VNE which in many case I understand, is set only 5-10 kts below the point at which things start fluttering I gather!
25th Jun 2004, 22:35
Sadly, Gorilla, life in the human World is not always as simple as it is for you primates.
The phrase "It was reported the other day" throws many variables into the discussion. We must question both the expertise and the motives of the reporter in this case, particularly as he uses the expression 'Vne', which is very seldom used in the helicopter fraternity.
It would be very unusual for a SAR helicopter to be capable of flying above Vne (or its rotary equivalent) in sustained flight. Not quite so unusual for it to be capable of flying above Vmax: an entirely different prospect, which a lot of SAR captains would happily contemplate in life-saving situations. (See 2ndclasscitizen's post)
Thankfully, the human race has evolved beyond the simplistic Gorilla's view, and some of its members are morally and intellectually equipped to make judgements on complex issues.
25th Jun 2004, 22:43
'bout time for a JF input before this goes off the rails?
25th Jun 2004, 23:23
So let me get this straight:rolleyes: In certain circumstances busting and airframe/engine limitation is acceptable based on the scenario presented:sad:
Ever wonder how these limitations are derived:rolleyes:
VNE, VMAX, VNO, blah blah are exactly that...........so why bust them:}
Gorrila is quite right to point out that more often than not us "educationally challenged" souls find ourselves hooked on to the gearbox of some medal hunting feckwit who believes his understanding of the airframes limits is far superior to the specialists the manufacturer employs :rolleyes:
all spelling misatkes are "df" alcohol induced
26th Jun 2004, 13:19
"In certain circumstances busting and airframe/engine limitation is acceptable based on the scenario presented"
OF COURSE IT IS
SAR crews are frequently faced with this quandary, and they often sacrifice (for example) a little fatigue life in order to help a human one. The decision is based on a multitude of factors, and the crew's knowledge, training and experience can help them make it. Safety of the aircraft and crew is paramount, they all understand that the very worst thing they can do for a survivor/casualty is to become casualties themselves. In my experience these decisions are crew-based and I have never known SAR engineers subsequently to show anything but understanding for their difficult plight.
The vast majority of aircraft engineers are intelligent people who undertsand the operational requirements of their and their aircraft's role. Clearly there are exceptions to this.
26th Jun 2004, 13:21
The key point is knowledge of the limits, the reasons they were set and the consequences of exceeding the limit. A really good captain will know the above and hopefully make a reasoned decision. Just because a limit is exceeded doesn't necessarily make him a bad pilot.
On a helicopter, maximum IAS limits are set to avoid excessive vibration and a reduction of fatigue life and not for reasons of "aerodynamic flutter". In extremis, depending on type of aircraft, retreating blade stall may also be a limiting factor, subject to all up mass. It isn't really possible to directly compare helicopter limits with those of a glider or any other fixed wing though.
Transmission torque limits are set for similar reasons. In some cases, helicopters transmissions are able to carry quite a bit more torque than the published limit, but at the expense of possible excessive wear. It really depends on the weakest part in the transmission.
If the situation justified it, I would possibly risk the life of a machine to save human life, provided I was sure there was no danger to persons on board. One vital thing is that if a normal limit is exceeded, it must be documented so that corrective engineering maintenance can be carried out if required.
A few years ago I overtorqued a fully laden S-76 because on approach to a newly refurbished and supposedly FOD-plodded and cleared helipad, a hidden piece of wood suddenly flew up in the downwash towards the tail rotor. The crewman screamed that it was going to hit and full power didn't give sufficient avoiding action so adrenalin made me keep pulling until he stopped screaming. The overtorque (fairly large but short lived) was properly written up and no damage was found by the engineers. I was not criticised but then we (7 of us) would possibly have been dead had I NOT exceeded the normal transmision limits.
26th Jun 2004, 16:35
It is the manufacturer who sets Vne!!
In order to get certification of a fixed wing design the manufacturer has to NOMINATE a speed for the design known as V design (Vd). If he succeeds in demonstrating in flight that all is well under these conditions then he is REQUIRED to reduce this by 10% and set this lower speed as Vne
Dangerous aeroplanes are those where there is enough power to exceed Vd in level flight or with a small rate of descent that could arise from a moments inattention. There have been one or two examples of this problem in the past and (reasonably) they have attracted a Vne lower than 90% of Vd.
Some aircraft in development programmes get modified for various reasons and this can call for an even lower Vne to be set temporarily. I believe this was one factor in the Vulcan accident referred to earlier.
Please note I am not saying identical rules apply to rotary wing certification as I have never been involved with that. But I would be surprised if the situation with choppers was not similar. Perhaps a rotary wing tp will comment.
26th Jun 2004, 17:56
Apologies, my only excuse being that the great god "San Miguel" clouded my response. The examples you give are spot on and I am now climbing back in me box:O
all spelling mistakes are "df" alcohol induced
27th Jun 2004, 07:15
Re the RN SAR scenario, we just don't know what happened. Hopefully, if it happened, the reason we know is because the crew came home and owned up.
In extremis, potentially trashing an aircraft, and risking the crew, can be justifiable but the captain had better be prepared to stand up and explain himself whatever the outcome. From personal experience, senior officers with a fixed-wing background, who may see SAR as rather peripheral, are unlikely to understand or be sympathetic.
I took a SK into a situation some would not approached and came away with people who would otherwise have died (smiles all round) but the aircraft was badly damaged in the process. This did not involve exceeding limits (unless of natural caution!) but the implications are similar and the evidence more obvious. I would put this alongside battle damage as "what can happen when you take calculated risks to complete missions" Again, being honest and being able to justify it afterwards is all important.
OBTW, the whole crew discussed the risks in advance and agreed with the plan so let's drop this chip-on-shoulder line about medal-hunting, two-winged master race etc. blah, blah.
As for exceeding aircraft limits, this is not to be lightly undertaken. As for guessing what the designers factored in, forget it. Especially with helicopters, its is an imprecise art and aircrew should treat limits with respect. If it happens, minimise it, get the aircraft back in the hands of the engineers asap, own up and hope it doesn't fall appart two flights later with your mates aboard.
I can't think of a helicopter that I have flown where you could exceed Vne in the cruise without pulling higher than max continuous power.
Best range speed is usually approx equal to Vno (roughly 10kts or 10% below Vne if memory serves!) so, unless they were experiencing high head winds, there wouldn't be any benefit from exceeding Vne.
I would put this part of the story down to inacurate reporting - there again I am always open to being proven wrong
27th Jun 2004, 15:13
Actually, some rotary Vne limits are set because they cannot be reached without a ridiculous rate of descent being reached, so why bother going faster. eg EC-155 Vne 175 kts, manufacturer has taken it to 210 kts and the head/blades to 240 on a dauphin.
On the other hand, they also take into account the wear and tear on the controls and hydraulic servos; ie componant life consideratioons.
I don't think one can consider exceeding Vne or any other FLM limit deliberately without snagging the aircraft after; not really fair on your colleagues, or you the next time you fly it, really?
27th Jun 2004, 16:26
Can and aircraft limit be broken for SAR?
It's really quite simple. The rules must be followed. Whenever a crew operates outside the rules, they may be subject to the consequences. With valid reasons to operate there, I'd hope that the consequences would be the exception.
One of the mistakes that is frequently made is the crew isolates themselves. Instead of being a part of a National SAR response, they become, in their mind, the only resource. If your rules, crew or machine is not capable of completing the mission, then perhaps there is another resource that can.
Once you determine that there is no resource, then the outcome of repenting must be compared to the outcome of pressing. Sometimes your best efforts are still not enough. If that's obvious early on, then don't break rules.
You now deem that there is a good reason to operate outside your rules (risk analysis) and there is no other resource to complete the mission. Now is the time to confirm your crew agrees with your plan, and if so execute it.
Sometimes all of the above happens in seconds, sometimes it can happen whilst flight planning on the ground.
I can give examples of exceeding parameters to save lives, exceeding parameters for no good reason, turning down missions that could have been completed by exceeding parameters (some with fatal outcomes), etc. In all but one of the examples, neither I, my peers, nor my superiors found fault in the decisions. In the one exception only a debriefing occurred.
The crews should never feel pressured to go beyond. When a National SAR system is designed, the limitations of the resources would have been considered. A high percentage of mission completion will be a part of the plan, but it won't be 100%.
Time to sum up. SAR crews don't have blanket authority to break rules. If they choose to they must consider other resources, risk analysis, the crew, the machine, and the rules. They mustn't feel pressured to provide what their country has chosen not to provide. All that being said, I think the best way of summing this up comes from our orders:
A too literal interpretation of these orders, that negatively affects the provision of SAR services, was never intended.
27th Jun 2004, 21:15
A thread on this topic has now also been started on the rotorheads forum. If I knew how I would post a link but maybe someone else will do it
27th Jun 2004, 21:30
Very gracious of you.
I do hope you're on holiday at the moment, as there are far superior beverages available in Wilts!
I am confused. Quote:
"Can and aircraft limit be broken for SAR?
Then followed by a somewhat cotradictory post, in which you seem to agree that a sensible risk assessment must take place.
27th Jun 2004, 23:21
You're not allowed to break a rule. When you do so, you do so without consent. Thus the answer to the question remains 'no'.
I admit this may seem a bit confusing, however that must be the attitude to go in with. I know of many people who were very lucky, and others who weren't so, that got themselves into trouble by thinking that while on a SAR mission they operate without a rule book.
The Swinging Monkey
28th Jun 2004, 06:44
As many of you will know, I AM ex SAR helos, and whilst I cannot confirm or deny it, I would treat the 'report' with a great deal of caution.
I would be astonished if the said helo managede to get faster than Vne (assuming it was under control of course!)
Rules are very very rarely broken, and I can say that I have never knowingly broken them, or even been able to break them, although I will admit that long distance SAROPS have called for some extremely accurate calculations which have been a bit 'iffy'
Gorilla, you are a fool Sir, and your comments prove it.
Kind regards to all SAR boys and girls
The Swinging Monkey
The Nr Fairy
28th Jun 2004, 14:21
Here's the link to the Rotorheads thread :
17 years, manandboy
28th Jun 2004, 16:20
It appears that there are a lot of people out there, who from the cosy confines of their computer desks are making assumptions based on less than 100% of the true facts. (For a change)
YES there are rules that should never be broken....
YES there are limits that should never be exceeded.....
YES there are situations that should never be approached.....
Ladies and gentlemen, let me ask you this:
IF you are unfortunate enough to crash your aeroplane into the sea, and you are just outside the radius of action of any of our SAR assets, if they stuck to all their limits, and
IF the weather was so bad on scene that, even if they did make it to you, they would be operating beyond their legal limits, and
IF there was a no chance that they would have any fuel remaining for an instrument recovery, if the bad weather caught them out, and certainly no diversion fuel, as is required by the big book, (or sets of books now), thatís if they reached you, and if they found you in the fog, and if they managed to rescue you,
In fact to lift at all would be just stupid.....
Would you want them to try?
28th Jun 2004, 18:06
I would agree wholeheartedly, however as the 'facts' of this particular incident are now emerging on the rotorheads forum it would appear that a nearby RAF asset was capable of conducting the mission within their limits as they carry a greater fuel load. So why did the RN crew push on? Service rivalry perhaps?
28th Jun 2004, 22:54
Surely Vne is set a certain percentage below the point when the test pilot chickened out....
29th Jun 2004, 09:33
Please read John Farley's post on this thread before posting yours!
Triple Matched TQ
29th Jun 2004, 21:25
Whilst around the house of triple Torque I was made aware of the recent interest in my "INCIDENT". As the pilot of the aircraft in question I am obviously interested in all of the points of view that have been expressed - some sensible - some based on rumour (the purpose of this site??) - and some perhaps from self proclaimed experts who I hope never have to come to save me.
I have nothing to hide and so shall set the story straight. As some of the more informed (experienced) commentators guessed straight away - the limit that was broken was actually Vmax and not Vne, (although Vne is not published for the Sea King - Check with the TPs and Design Authority at Westlands if you disbelieve that).
Whilst I can't address all of the points raised individually I'm sure that the answers will become self evident.
The call came from the RCC that a suspected heart attack victim was currently on a yacht 192 nm south west of the Scillies and required immediate assistance. Our ROA for the conditions of the day was 195nm (with all necessary safeguards built in). We launched and refuelled to max at the Scillies and then relaunched. After about 20 - 25 mins en-route from the Scillies (55 mins into the job) we received an updated position that now gave his location as 205 nm SW of the Scillies. This now put the job beyond our declared range and if this had been the case from the outset it would have been passed to Chivenor automatically by the RCC and by matter of course had we received the info much earlier on we would have done the same. So for the commentator who suggested inter-service rivalry - grow up because you are obviously part of this problem. We have an RAF SAR pilot on exchange and by the way Chivenor are covering our SAR during an annual dining out night next month.
Now faced with a stark choice - either come up with a plan to continue or call the RCC for Chivenor - this would then entail at least another hour delay - for a guy in the throws of a heart attack??? Our on board paramedic advised that the benefit of every minute early would have a direct effect on the subsequent longevity of the patient.
Now with a more accurate fuel burn calculation we assessed that we could reach the yacht but only achieve 10 minutes on task - which even had we been piloted by an RAF crew might not be long enough for a night time highline transfer (Nil moon - sea state 6). Therefore we took advantage of the strong tailwind and climbed with the resulting reduction in Vmax and achieved an altitude that gave an airspeed that exceeded Vmax by 8 kts (for about 15-20 minutes) which would then provide 20 minutes on task with a refuel required at Scillies prior to our return. This deliberate exceeding of Vmax was discussed and although only an average QHI I was nevertheless aware of the implications of exceeding Vmax in the Sea King - namely the initial danger of retreating blade stall. Now for those of you that are familiar with the expression of "flying on the cruise guide" - this is a practise much frowned upon by the RN, however is an SOP for S61 ops in the States. Basically you get a vibration indication on a gauge that is quantified by a detector on the primary jacks with a green and red (unacceptable) band on the gauge. We experienced a low green reading throughout. And dare I say it to the non Sea King guys but the old girl soon tells you if she is not happpy.
Now I don't condone the willful exceeding of any limits unless you can a. justify the requirement and b. are aware of the implications of so doing.
The various other contributors to this subject confirm what was suspected by me and later confirmed by Westlands. Vmax is 10% less than the Vne which is 10% less than Vd which is the max design speed.
In addition to this course of action we requested that the RCC arrange for the in company MayDay relay merchant ship to attempt to transfer the casualty and make best speed towards us. This was eventually achieved and a transfer was completed from the merchant ship in 8 minutes (not bad for RN SAR!!).
The aircraft was then returned (within Vmax) but now into the known about strong headwind although the fast transfer, better than worst case fuel burn etc allowed a return to Culdrose to be made and a refuel was required even though Treliske was only 8 minutes further flying since obviously flying below MLA was a limit with very different implications and one we were not willing to exceed!! I take the hit that we then took off in an unserviceable aircraft (exceeded Vmax) however after nearly 5 hours in the saddle and approaching midnight I beg consideration and forgiveness.
The patient was discharged from hospital 3 days later with a clean bill of health and no lasting ill effects (he had suffered the initial stages of a heart attack) about the same time that I was warned of possible Courts Martial proceedings against me.
The Courts Martial threat receeded (I can now sleep at night!! without the threat of jail) and we all agreed not to break any limits unless we could a. Justify them and b. understand the implications of doing so.
We reported honestly and accurately our exceeding of Vmax which lead to routine inspections and a seviceable aircraft shortly afterwards.
I do stand by the decisions made although accept that a whole raft of other opinions may be offered although as one commentator stated you don't know unless you are there!!
30th Jun 2004, 05:22
Triple Matched TQ:
Thanks for the facts. It seems to me that you did the right thing. Very unfortunate that anyone mentioned a court martial, good that it wasn't pursued.
Well done on the mission! Please pass this to the crew.
The Swinging Monkey
30th Jun 2004, 06:22
Triple Matched TQ
Utter respect to you (and thats from an ex crab!)
I'de have no hesitation in flying with you, anytime, anywhere.
I take my hat off to you and salute you Sir.
The Swinging Monkey
'Caruthers, a large bottle of Grouse for TM TQ'
30th Jun 2004, 10:22
BZ TMTQ, and all your crew.
17 years, manandboy
30th Jun 2004, 15:08
Lets just hope all those armchair pilots, who obviouly knew all the facts, and all your aircrafts limits inside out, and have obviously spent many years in the role of Search and Rescue, have learnt something.
2nd Jul 2004, 07:49
First Gulf war, 3 hercs at 30 minute spacing heading for ex-lightning hi- altitude Saudi base. I was number two. We all had problems getting airborne and making altitude. We worked some figures back thro ODm and came out with ridiculous weight. Advised other a/c on radio of conclusions. No 1, ignored them, according to crew, hit ground with hell of a thump and crack somewhere up in centre fuselage. I landed using shed loads of power and most of 12000ft runway (yes, speed way above limiting so I held the nose off.. ) and taxied and blocked him in so we could weigh the freight as it came off.....surprise surpise, load was marked in kilos instead of pounds as movers had said.. Point is, had manufacturers limitations been set in concrete I think we would have all had broken main spars instead of the one who ignored best advice.
The broken one was recovered to big "A" without incident, however the subsequent t/o caused fun and frolics as the hot air ducting was also cracked and burnt thro the wiring to the no's 1 & 2 engines or was it 3&4. It was patched up and flown back to UK un pressurised, day light only, within sight of land!!
2nd Jul 2004, 09:07
Sounds like a job well done, also from an ex-crab!
Still a bit confused by heedm's posts, but his latest would seem to agree with the general attitude that there is some flex, in some rules, as long as you apply sufficient thought and care.
I'm sure a lot of survivors are just that because of our SAR force's flexibility and professionalism.
2nd Jul 2004, 17:04
Obviously a job well done and properly thought through. I cannot even start to imagine why the powers that be thought that taking Courts Martial proceedings against you would solve the problem. If that is their attitude then nobody will ever own up to exceeding limitations (whether by accident or deliberately in the course of duty) and we will all end up flying unserviceable aircraft! :ok: :ok: :ok: :ok:
2nd Jul 2004, 22:24
A copy book rescue by my reckoning. I'm just astounded that you were threatened with a Courts Martial!
I have some 10 years of experience doing SAR around the SW and 14 on the 'King'. I think it would be fair to say that on every SAR mission I flew on, where time was of the essence, we exceeded the calculated VMAX for the day. Big deal. You could push the 'King' all you wanted, but she soon told you 'don't go there'. The torque/ptit/vibration et al, soon tempered your enthusiasm for the task in hand.
The calculations that are done for ROA, PNR, CP, 5%, fuel burn, SSE, etc, etc, at the start of a watch are bog standard, and do not account for the actual 'being there'.
We were there to do a job. A job for which we had been trained. We were fully aware of the implications of breaking an aircraft and so did not stitch an oppo.
Spanish Waltzer: You don't live at the 200 mile limit, do you?:ok: the 3/3A fuel is about 30 minutes more than the 5.
I think I've lost the thread of what I was trying to say, 'cos it's late, but rotary limits do have some flex; just ask an Op Telic Puma operator;)
TMT, to sum up, I think you can ignore most of this thread and continue to do what you do best. Fly professionally.
PS. Still throwing dice for the tea?
Pub User, the reason I say that you can't break rules and then condone instances where you can is to avoid having crews with the attitude that there are no rules when on a SAR mission. It happens. See Spur Lash's post.
3rd Jul 2004, 11:00
If you stay within the "Rules" (SOP, FOB, Flight Manual etc) you are legally covered by the organisation you work for; they remain vicariously liable for your actions. If you step outside these Rules you are on your own in a litigious sense.
I have broken the rules and cut a hole in a tree canopy with a rotor disk to rescue a man, it worked so I got a badge to wear. If it hadn't a crew of four could have died and I could have been negligently liable and possibly criminally responsible.
This is often the reason that aircraft captains who make that step beyond organisational responsibility are often threatened or even taken to courts martial.
3rd Jul 2004, 11:21
Contrary to your last post, at no stage did I say that there were no rules on a SarOp, and we most certainly did not fly with a 'no rules' attitude. We were always fully aware of the rules and complied with them.
However, the knowledge we had of the rules, enabled us to make informed decisions within the flexibility of helicopter operating parameters. As has been mentioned previously, it's not that easy to push a Sea King far, because it just won't let you!
3rd Jul 2004, 18:21
I remember the tragic loss of the Moushole Lifeboat many years ago. The Coxswain rejected 2 crew members because the weather was so foul that he would only take one person from any Family.
The SAR Wessex from Culdrose was on station but the Captain (a USN Lt) refused to allow the Crewman to go down because of the appalling conditions. The weather conditions were way outside the limitations of the Wessex but they remained on station.
The crew of the distressed vessel and the entire crew of the Lifeboat perished in the tragedy.
The USN Captain paid his own fare across the Atlantic so that he could pay tribute to the RNLI crew at the Inquest. He described how the Lifeboat had actually timed a run and "beached" itself on the side of the Ship so that the crew could get aboard. This they did but the Lifeboat itself later succumbed to the Elements.
If you are trying to save life then the normal "Rules" for Peacetime Operation do not necesarily apply.
I see on SKY News that HMG are going to introduce legislation that will allow Ambulance Drivers to "jump" Red Lights in an Emergency thus bring them into line with the other Emergency Services.
There are times when normal "RULES" have to give way.
Capt W E Johns
3rd Jul 2004, 23:14
So you're at war, and on the day the General says "over the top lads, into a hot LZ with a load of soldiers and I expect a few of you won't come back". Flight safety? MAUW precludes carrying that extra box of ammo for the troops? Arse. Salute, yes sir thankyou very much, and execute.
Now I'm not suggesting that SAR always justifies breaking rules (although it might) and I'm not suggesting that wartime ops mean flight safety is ignored (but it might). War, by definition, is not safe. There is a sliding scale of mission vs safety, starting at commercial passenger operations and ending in the commitment of military resources to a high-risk mission.
If you're exceeding the MAUW, make sure you mention it. If the plan for the battle includes losing some machines due to disregard for the orders, then they won't be surprised. However, if the plan doesn't call for that loss then perhaps there's a plan to use those machines tomorrow.
It was mentioned before that the rules are not just for safety of the crew, but also they indicate what risk has been accepted by higher command. If the risk has been accepted then so have the consequences which include the chance of loss of resources.
This is quite valid in the SAR scenario. If you purposely break a machine to try and complete a mission that you can't otherwise do, then what happens to the following missions.
Again, I'm not saying don't break the orders, just make sure you have considered the consequences.