Fast cruise in a Cessna 152

[Molesworth 1]

Is there any harm in cruising a Cessna 152 at 100 knots apart from burning up a lot of fuel? I was taught to cruise at 90 but a year or so ago an instructor told me to speed up to 100 to "save time"?

Does anyone know what the fuel efficiency difference is?

[Neptunus Rex]

Fast cruise in a Cessna 152Molesworth 1, you have just redefined 'oxymoron.'

[Katamarino]

I suggest consulting the POH (or googling for a POH if you don't have one to hand). It will answer everything you've asked.

[Molesworth 1]

NR - Ok I'll rename it to "Faster than normal cruise in a Cessna 152" :cool:

POH says VNO is 108. So it's fine and obviously in the green arc.

At sea level we have 4 hours endurance at 65% power and just under 3.5 hours at 75% power. So how do you know when you are using 75% power?

[Mark1234]

RPM and density altitude. Again, there's a power setting table in the POH :ok:

[Katamarino]

If you look in the Performance section of the POH (probably chapter 5) you'll find a table linking altitude, temperature and engine RPM to percentage power. For example, at 2000ft and standard temperature 2400 RPM will give you 75% power, and 101 kts IAS.

[Molesworth 1]

Yes, I see it. Hmm.. interesting. So if you're on a relatively short trip and you're paying by the hour and not for the fuel, then it makes no sense trundling along at 90 knots?

[Katamarino]

Indeed! At our club you pay by the Tacho hour, or the actual flight time, whichever is higher...the trick is to run the engine as fast as possible without getting the tacho time over the actual flight time. It's a fine balancing act :ok:

[Molesworth 1]

No wonder the flying club in no hurry to show me the POH!

[Jhieminga]

Molesworth, please do yourself a favour and read the manual from cover to cover. But to get back to your question, here's the powersetting table from a C152 POH (check if it matches your aircraft before using!):

http://www.vc10.net/div/C152_powersettings.jpg

If you're going cross-country find the row for the pressure altitude that you'll be flying at and the column for the temperature. Then choose a %power from the '%BHP' column and use the numbers to the right of that. Set that RPM when settled in the cruise and keep it at that number. Keep in mind that you'll need the engine at 'Recommended lean' i.a.w. POH chapter four to get the fuel flow numbers mentioned here, and even then add a percentage to your trip fuel for safety's sake (5-7% would be my recommendation but more fuel is always better as long as you're within the W&B envelope).

Example: For 2000 feet on a standard day, 66% gives you 96 KTAS at 2300 rpm.

[Molesworth 1]

J. Thanks - I discovered this page all by myself and not rocket science to work it out!

Methinks you have missed my point. If I'm not on a flight of more than 2 hours there is little point in maximising fuel efficiency. Flying is expensive enough as it is without having to worry about saving a couple of quid off the flying club's fuel bill. They are making good money from me as it is!

SoCal App: You don't get much joy at flying clubs this side of the pond with a request to look at the POH - or any other aircraft documents for that matter. It's a case of sign the tech log - don't take it away - fill it in when you get back. Any problem with the a/c tell us and we'll write it on a sticky note for the maint team.

There is no legal requirement to carry the POH, even when travelling to another country - and I know of no one who does. Please explain - AR(R)OW check?

[Jhieminga]

True, it's not rocket science, and I may have tried to write a 'dummies guide to....' when that was not called for. But as pointed out before a good read of the POH would have answered your question and personally I think it is compulsory reading before setting foot in an aircraft. If the club doesn't let you, then hire somewhere else.

Going back to your original question, indeed you might just as well cruise at 100 kt instead of 90 without doing harm to the aircraft. As you say it is easier to not maximise your fuel efficiency. Two things though: 1. the power settings in that table are those at which, or between which you can/may cruise. That is useful information which defines your playing field. 2. Operating an aircraft efficiently shows good airmanship. That's never a bad thing. You never know when you might find yourself in a situation where you'll need those last drops of fuel and then you'll be glad you saved them.

Edit: Over here the POH is part of the ship's papers, you are required by law to have it on board. I don't have time now to refresh my memory as I cannot remember if that is EU law or Dutch law. Someone with more knowledge than me of UK air law will surely answer that question.

[Molesworth 1]

Yes, of course J - I take your point. For me, conserving fuel in an emergency situation would involve flying slowly with a lean a mixture as possible. This is borne out in the table, but goes without saying even without reference to any table.

The table is interesting all the same - thanks!

[x933]

Stay at 90kts. Simple reason, it makes the maths easy. 90kts is 1.5nm/minute, 100kts is 1.6667Nm/Min - which apart from being infinately harder to work out "at a glance" - isn't enough to make a difference in the great grand scheme of things.

And flying schools - contruary to your belief - don't make a huge ammount of money from you (Unless you're on an integrated course). Margins are very slim...

[Molesworth 1]

Just having a re-read of Jeremy Pratt's Air Law book.

He does indeed stress familiarity with the POH for safely and legal reasons. It's strange that flying club's like (and often require) you to read their Standing
Order book but you are never ever offered a full POH. Usually all they show you (if you are persistent) is a ring binder/plastic folder with landing/takeoff and W&B tables.

[Fuji Abound]

I thought a 152 had just two throttle settings - open and closed, there is so little difference in between.

[EDMJ]

There is no legal requirement to carry the POH, even when travelling to another country

How do you do your weight & balance calculation without it? How about calculating required runway length? I like to bring it with me. Better make sure you bring it with you if go to Germany (fast cruise or not) as it has to be onboard the aircraft there.

Anyway, sounds as if a flight is something which you just need to get over and done with in a hurry. Don't you enjoy it?

[Pace]

How do you do your weight & balance calculation without it?

edmj

I think you will find that most flight school ops dont fit in on the weight and balance data for a 152? and looking at the size of some of the occupants who get in there! not surprised :ugh:

Is there such a thing as a high speed cruise in a 152 :E i thought they only did slow speed to slow medium speed ;)

Pace

[Molesworth 1]

How do you do your weight & balance calculation without it? How about calculating required runway length? I like to bring it with me. Better make sure you bring it with you if go to Germany (fast cruise or not) as it has to be onboard the aircraft there.

Anyway, sounds as if a flight is something which you just need to get over and done with in a hurry. Don't you enjoy it?

Weight & balance sheets are available, generally, as are takeoff and landing tables. Do you work out weight and balance every time you fly? According to the sheets you are outside of limits if you take off in a 152 with two people and a full tank. That would rule out practically every student and instructor flight.

Yes, I do enjoy my flying, thank you. Sometimes I fly much slower than 90 knots, sometimes I fly faster. Sometimes I need that extra speed so that I can get to a destination that otherwise would be outside my budget.

I will remember to bring the POH with me if I should ever get as far as your country - doubtful as that might be in a Cessna 152!

[Molesworth 1]

Hands up all those who did their PPLs in the UK in a Cessna 152 and ever laid their eyes on a full POH!

These are about as rare as a Shakespeare first folio. The type is all wonky like it just came off the trial run for the 15th century(?) Gutenberg printer. Reads somewhat like the instructions for operating a washing machine. Did you know for example, that the proper way to ditch a 152 was to descend at 55 knots and land with a level attitude? And that the way to stop a spin is simply to let go of the controls? And if you find yourself in IMC, then fly with your feet?

[Pace]

Molesworth

Heard all those as well as if your inverted in one your probably in Australia ;) as for engine start? "Wind the propellor between 30 and 50 times before letting go".

Pace

[Fuji Abound]

I know of a 152 POH making up for a missing leg in my old flying club but you cant remove it becaue the coffee table would fall over - does that count?


Is there such a thing as a high speed cruise in a 152 http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/evil.gif i thought they only did slow speed to slow medium speed


Pace - now I know you are an optomist - delete the medium and you are just a realist. The one time I tried one I found as I opened the throttle the noise got a bit louder, but nothing else seemed to happen.

[Molesworth 1]

The PA28s at my flying club go even slower.

[Piper19]

I always cruise at 2350rpm, gives me 95kts, done that for years, that's also how I did learn it. 100kts would be possible but keep cruise below 75%.
152 and speed just don't go together (altough I used to think it was fast when I transitioned from the Cub)

[Molesworth 1]

Piper19. That sounds like a good compromise.

When I did my skills test I had a rather large examiner and I worked out that with the two of us there was room for only 5 gallons of fuel! Needless to say we needed more than that for a two hour checkout and I added enough fuel for an endurance of three hours. The examiner had absolutely no problem with this.

I know that with two people of average weight and a bag of less than 10kgs, average temperature at sea level, W&B is not going to be a problem. Anything above that - say a box of wines from L2K I recalc the W&B. I have the graphs on an app on my iphone.

[EDMJ]

I think you will find that most flight school ops dont fit in on the weight and balance data for a 152? and looking at the size of some of the occupants who get in there! not surprised

According to the sheets you are outside of limits if you take off in a 152 with two people and a full tank. That would rule out practically every student and instructor flight.

I fly from an airfield with a 400m long (short?) paved runway at 1,842 ft MSL having a forest at one end. The local flying school has C172's and C152's. I can ensure you that such performance data/calculations is/are taken seriously :cool:

[FlyingStone]

Actually yes, I have all the datum in a small spreadsheet,
I fill in the blanks for front row px, second row px, baggage and fuel and it works it out - with today's date and the tail number,
It create the limits and graphs it.
Print and put in in binder - all ready for the unsuspecting ramp check. Takes all of 30 seconds including the time to print it.

I have the same thing here, I just fill in the data (weights, fuel) and the expected duration of flight and it automatically calculates W&B at takeoff and landing and puts both values into chart with envelope - it took me few hours to create it, but I now need 30 seconds to do W&B for entire flight :ok:

The two-seater W&B issue has been discussed many times, they are indeed a little more restrictive than four-seaters, but most of them have no problem with weights over MTOW, given that you don't have a very short strip and/or large obstacles. The most important thing is to stay withing CG limits, even if you are couple of pounds over MTOW.

[TractorBoy]

You don't get much joy at flying clubs this side of the pond with a request to look at the POH - or any other aircraft documents for that matter. It's a case of sign the tech log - don't take it away - fill it in when you get back. Any problem with the a/c tell us and we'll write it on a sticky note for the maint team.


You're not flying from a certain airfield in Essex just south of the M25 by any chance ?

[Old Akro]

In the words of Roy LoPresti: "Speed is not the most important thing....it's the only thing".

[Pace]

I did my PPL in a 152 over 20 years ago and now fly business jets in the upper FLs. Flew one not that long ago and it was still a load of slow fun with bags of character.

We probably loose sight of the low and slow drifting over deserted countryside one early summer morning, seeing the chickens run round the farmers yard the cows casually glancing up as you drift by a few hundred feet above. Avoiding the shot as a farmer let off both barrels in your direction :E Ahhh Bliss!!! what memories. That was real flying.

The 152 ;) Still remember the aircraft trundling in for full fuel while the next student (16 stone) jumped in with his instructor for the next sortie. Never time for W and B calcs, the little plane never knew what they were anyway.

Pace

[Fuji Abound]

Pace - actually, I agree it is a great aircraft, which has stood the most important test of all, the test of time. There are plenty of skills to learn in a 152 and to rekindle the most basic pleasures of flying. The 152 will seemingly put up with all sorts of abuse and will rarely bite the hand of its master. It is also one of only two aircraft I have managed to fly backwards in. :)

[A and C]

As an instructor I am much disturbed by this thread, to have people with PPL's who have never seen the POH is a damming condemnation of some parts of the flight training industry, I can just see the trouble that would come from the accident enquirey that found that the (now dead?) student pilot had never set eyes on the POH. My guess is that the CFI & instructor could well end up in jail.

For my part I have a "POH quiz" that I put in front of the student at an early stage of training (always before the first solo). This open book quiz about the aircraft and its systems is intended to get the student looking for the anwers in the POH and so getting to know how to find the data that they will need for future flying. It is a very productive way to spend a rainy afternoon.

[Pace]

A and C

Not wishing to take away from the seriousness of your arguement re W and B which is very important in any aircraft I am sure most who read my posts realise that I am joking about the aircraft and taking affectionate shots at it ;)

Having said that I do hold with seriousness that many flight schools have flown the aircraft without consideration for the W and B. I witnessed that many times on busy weekends in the past.

Pace

[A and C]

My post was not intended to be a pop at anyone except those who hide the POH from student pilots.

[conflict alert]

Is there any harm in cruising a Cessna 152 at 100 knots apart from burning up a lot of fuel?

no
don't ever exceed VNE and know what your rough (turbulent) airspeed is.

[Pace]

Conflict

no
don't ever exceed VNE

isnt VR and VNE the same in the 152???

I thought THE 152 was next years choice for the Red Bull air racing series ?

Pace ;)

[conflict alert]

cheeky:D

I thought THE 152 was next years choice for the Red Bull air racing series ?

how painfully boring that would be

[Molesworth 1]

All the stuff in the POH is part of the PPL syllabus but in a generic sense. It's strange that students aren't shown the POH of the aircraft they typically fly so that they can see a practical example.

It seems also that there are different versions of the 152 POH around depending on the year and model. In my experience every instructor has his or own idea how best to fly the Cessna 152. What one instructor recommends another will tell don't do it as it will kill you.

[Molesworth 1]

PPL's who have never seen the POH


Maybe it's because it's an important document that goes with the C of A, is kept in a safe and is too precious to allow out for reading by students with their dirty paws. Bits of this holy grail are photocopied so the student has something to show the examiner on Skills Test day.

Paradoxically it's so essential that it winds up being no use to anyone.

[Big Pistons Forever]

Unfortunately there seems to be a general tendancy to not pay a lot of attention to the POH in the flight training environment. This is unfortunate
because there is a wealth of important info in the amplified procedures section of the normal procedures section. It is also important to note that a sheet of paper with the emergency procedures copied on it is not enough. The emergency procedures section of the POH has an additional narrative for many of the emergencies which can be critical to properly dealing with some in flight emergencies. For that reason when I instruct, every simulated emergency starts with the memory items, followed by the emerg checklist of which the last item on every emergency is the POH page reference. Obviously I expect the student to use his/her judgement as to when it is apropriate to go to the POH given the situation. The hardest part of instructing is getting the student to stop rushing through the checks. There are almost no emergencies that do not give you time to calmly asess the situation and slowly and methodically work through the checks.

[Jhieminga]

From CAP 393, section 1, article 150:
Circumstances in which documents are to be carried
1 Subject to paragraph 3:
(a) on a public transport flight, Documents A, B, C, D, E, F, H and, if the flight is
international air navigation, Documents G and I must be carried;
(b) on an aerial work flight, Documents A, B, C, E, F and, if the flight is international
air navigation, Documents G and I must be carried;
(c) on a private flight which is international air navigation, Documents A, B, C, G and
I must be carried;
(d) on a flight made in accordance with the terms of a permission granted to the
operator under article 41(3), Document J must be carried.

Description of documents
2 For the purposes of this Schedule:
(a) 'Document A' means the licence in force under the Wireless Telegraphy Act
2006(a) for the aircraft radio station installed in the aircraft;
(b) 'Document B' means in the case of a non-EASA aircraft the national certificate of
airworthiness in force for the aircraft(b);
(c) 'Document C' means the licences of the members of the flight crew of the
aircraft;
(d) 'Document D' means one copy of the load sheet, if any, required by article 100
for the flight;
(e) 'Document E' means one copy of each certificate of maintenance review
required by article 25(2), if any, in force for the aircraft;
(f) 'Document F' means the technical log, if any, in which entries are required to be
made under article 27(2);
(g) 'Document G' means the certificate of registration in force for the aircraft;
(h) 'Document H' means those parts of the operations manual, if any, required by
article 83(4)(c) to be carried on the flight;
(i) 'Document I' means a copy of the notified procedures to be followed by the pilot
in command of an intercepted aircraft, and the notified visual signals for use by
intercepting and intercepted aircraft;
(j) 'Document J' means the permission, if any, granted for the aircraft under article
41(3).

Exceptions
3 (1) If the certificate of airworthiness includes the flight manual for the aircraft and with
the permission of the CAA, an aircraft to which article 83 applies need not carry the
flight manual as part of Document B.
(2) With the permission of the CAA, an aircraft to which article 83 applies need not carry
Document J if it carries an operations manual which includes the detailed information
specified at paragraph 1(s) of Part A of Schedule 8.

Definition
4 For the purposes of this Schedule, 'international air navigation' means any flight which
includes passage over the territory of any country other than the United Kingdom, but
does not include passage over any of the Channel Islands, the Isle of Man or any other
relevant overseas territory to which there is power to extend the Civil Aviation Act
1982(a)under section 108(1) of that Act.
Summarizing: there is no need to carry the POH in the UK unless you're operating a public transport flight (at least that's my understanding). As I mentioned before, in The Netherlands you are required to carry the POH so this bit of regulation is dependent on the country you're flying over/in.

[Molesworth 1]

J. Thanks for the reference.

The W&B tables. performance, take off and landing tables could be useful if you have to divert or land away and then decide to head off somewhere other than planned. On the other hand, refering to the book in flight might not inspire a lot of confidence in you from your passengers!

In the farce "Those Magnificent Men in their Flying Machines" there is the German Officer who flies by the book after the original pilot is incapacitated. "There is nothing a German Officer cannot do!". And Germany is one country where it is required to be carried! (Sorry - national stereotype - no offense intended!)

If the POH is available as a PDF there is an iphone app which allows you to upload PDFs to your phone. Might be more useful than the app(s) currently available called "C152 POH"

If the Netherlands is allowed to keep it's own rule maybe there's some hope for the IMC rating!

[Pilot DAR]

Summarizing: there is no need to carry the POH in the UK unless you're operating a public transport flight (at least that's my understanding).

It seems an important document even less well read than the flight manual would be the Type Certificate Data Sheet (TCDS) 3A19 in the case of the 150/152. It states in part (on page 13 of 19, for example):

"Equipment: The basic reqired equipment... must be installed in the aircraft for certification. This equipment must include a current Airplane Flight Manual...."

No doubt about that, it's got to be on board for the aircraft to be airworthy.

If that is not convincing enough, the TCDS requires (Note 2):

"The following informaton must be displayed in the form of compostite or individual placards. In full view of the pilot: "This airplane must be operated in compliance with the operating limitations stated in the form of placards, markings and manuals"." The pilot won't be able to operate in compliance with a manual, if it is not aboard!

There are a few very old aircraft for which a flight manual or equivilent was never issued. For all other aircraft, it is extremely likely that the approved Flight Manual must be carried aboard at all times. I suppose a copy would be acceptable, if it were a good, and accurate (properly revised) copy.

I occasionally hear whining here about planes, and the asking of questions which would be answered if the pilot read the instructions! Oh, can't find the instructions? Don't fly the plane! It's not legally airworthy! The aforementioned placard tells you so! (because you read the placard, right?)

Those of us who certify aircraft, go to immense effort to produce these documents. Owners - please provide them to the pilots! Pilots - please read them!

I've owned my plane for 23 years, and last week had to dig out the manual to answer some very fair questions, asked of me during recurrent training. Without the manual, no answer = no pass training!

[Jhieminga]

"Equipment: The basic reqired equipment... must be installed in the aircraft for certification. This equipment must include a current Airplane Flight Manual...."
Funnily enough an EASA TCDS does not include that sentence. I've only been able to check the FAA and EASA TCDS for the 172 though, there is no EASA TCDS for the 150/152 family that I can find. Older types were certificated in the individual member states so there is no database that I know of that holds those TCDS.

[Pilot DAR]

Funnily enough an EASA TCDS does not include that sentence

EASA TCDS #IM A 051 for the 172 has a very similar sentence on page 8. I propose a pilot certainly could not cite that EASA (or FAA) TCDS statement as permitting the aircraft to be operated without the flight manual aboard.

If the 150/150 (which are no longer current production aircraft) do not have an EASA TCDS, the FAA TCDS would be applicable in EASA land, per some agreemnt I would not know where to find. Therefore all of those aircraft are certianly bound by a requirement to have a FM aboard.

Elsewhere in the EASA 172 TCDS there are similar references to the placard requiring the operation of the aircraft in accordance with the flight manual.

I have known aircraft to be simply grounded, for lack of a flight manual (because a grubby handed student took it home) - (to another continent, in one case). The factory replacement manual (for a medium twin) was $1200.

[Jhieminga]

EASA TCDS #IM A 051 for the 172 has a very similar sentence on page 8. I propose a pilot certainly could not cite that EASA (or FAA) TCDS statement as permitting the aircraft to be operated without the flight manual aboard.
I read that and concluded from it that the aircraft must be operated in accordance with the specific manual stated, not that it must be carried on board. As for the 152 I agree that in that case the FAA TCDS is leading. Still, Dutch law specifically confirms that the POH must be carried while UK law doesn't. Strange.

But we're getting carried away here and drifting off topic. We don't need to dig up tons of regulations to agree that a POH is mandatory reading material and should be within reach when operating an aircraft.

We had a similar situation a few months back: one aircraft with missing POH and therefore not flyable, leading to a lot of shuffling of students and instructors across the fleet.

[Pilot DAR]

the poor old dear will be slower than she was when she was first born, (made) even with a new engine.

So, you're saying that it would no longer conform to its type design? You probably should not fly it.

The flight manual will provide performance information, which is based upon the actual results of flight testing a conforming example of the aircraft, generally at gross weight. If an aged example of the aircraft cannot meet the conditions of the type design, and therefore the flight manual figures, it probably needs some maintenance. I agree that some aircraft are flying with "tired" engines, and that will affect performance. Good engine maintenance is well defined, and easily obtained.

There would not be much point in defining and approving a type design, if the aircraft out there are not maintained to conform to it. When maintenance is performed, the maintenance release for the work accomplished, will generally say that the aircraft conforms to it's type design. It will therefore do what the flight manual says it will, or someone has missed something!

[Say again s l o w l y]

Molesworth, all I can say is that you have been trained by a bunch of chimps.

Go and fly somewhere that does things properly, because the stuff you've mentioned here is absolutely unacceptable.

[Molesworth 1]

Go and fly somewhere that does things properly

Are you saying that there IS somewhere that does?:}

[Say again s l o w l y]

Yes, there are plenty of places around the country that do things as they should.

Gash nonsense like that has no place in any flying organisation. It might be more common than I like, but it is by no means the norm.

If you are somewhere near the north side of London, I can point you in the direction of at least 2 places within 30 minutes drive that wouldn't dream of doing silly things like this. Sticky notes on techlogs, no access to the POH... Honestly, words fail me at how unbelieveably shoddy that is.

[Molesworth 1]

You will be pleased to hear that I have downloaded a 50 page version of the Cessna 152 (even this is "abridged") and will come in useful if the Cessna I am flying should have a slight problem (such as having to land without an elevator control).

Since I seldom fly any other aircraft (cost reasons mainly) it's good to know the old girl inside out.

I have also had my original question answered (more than a little thread creep!) and will consult the POH for the most cost effective way of flying (not from the clubs' point of view obviously - but then I'm still not in the league as students doing up to 10 power takeoffs an hour in the circuit - and they're the clubs bread and butter!)

[Molesworth 1]

no access to the POH


I have flown with at least four clubs and none of them have given me access to the POH!

[Say again s l o w l y]

Don't forget that POH's often have significant amendments over the years, so do be careful and the authoritative one is of course the exact one for the aircraft.

Having said that, any POH is better than no POH.

I cannot stress to you enough how important it is to have access to the correct documentation. If I was presented that scenario at a school, even as an FI with students waiting I'd walk out straight away and never darken their doors again. If they are gash with stuff like this, then what else is going on?

Edited to add:

I have taught in at least 10 different schools/clubs over the years and flown at many more. People can be reticent about allowing the "Holy Grail" out of their sight, however, you as PIC should kick up a stink until you see it.

I have always made the POH available to my students and members and they get quizzed on it regularly, with written tests that they must pass.

It sounds over the top, but it really isn't.

[Fuji Abound]

.. .. .. but does the little Lyco like being run at 100% power - or even 90% power, for any prolonged length of time?

[Pilot DAR]

AIM,

Not having easy access to a 152 manual, or knowledge of the atmospheric conditions in which you were flying, altitude, weight, accuracy of that particular airspeed indicator, the pitch of that particular propeller, wheel pants on or off, or minor factors like the cleanliness of the plane, I would not be able to form an opnion as to the performance of the 152 you were flying.

It's up to the pilot to be aware of the expected performance of the aircraft they are piloting, and thereafter during the flight take note of the differences between that performance, and what is really being achieved. This difference could be the result of an unexpected factor in the condition of the aircraft, or something really simple like the wind.

It is not wise to depend upon the published information to the point where variables are dismissed. Certainly, a suspected maintenance defect of any kind should be reported. If the plane is consistanly not achieving published performance values appropriate to it's configuration, that should be questioned.

Cruising at full throttle in anything other than circumstances of quasi emergency, is unwise. Though some smaller engines will tolerate it, most larger ones you might come to fly will not. Often, the small carburetted engines have rather poor mixture distribution at full power, which means some cylinders are working harder than others. In any case, the fuel consumption will be huge by comparison to "normal" cruise power settings.

As you fly, be aware of all of these variables, and how they will affect your flight...

[Pilot DAR]

just the fact that after 25+ yrs of use the wings will not be as smooth, the fuselage will not be at its best and as such when using the aircraft to its maximum it will not perform like it did out of the factory.

I don't agree for the reasons I have previously stated. With the exception of the paint being poor, and flaking off, or the plane simply being dirty, there is no reason whatever it should not fly as factory new. Particularly when it is being well maintained.

If the wings are not as smooth because of being wrinkled, the aircraft is in need of repair, and should not be flown in service. If the fuselage is not "at its best", I'd be worried. It's a semi monococque fuselage, and nearly all of its structure is on the outside. If the outside is not at its best, the plane is not as strong as it is required to be.

If someone is teaching you to expect less out of an aircraft because it is older, I suggest that you not accept this as being true. They are either poorly informed, or trying to downplay something.

The aircraft either meets its type design, or it does not. If it does not, it is probably not airworthy.

[Say again s l o w l y]

You do understand the difference between net and gross performance?

POH's are invariably based on a brand new machine being flown by an experienced test pilot. The chances of a 15,000hr baggy old 152 meeting those figures when flown by an average PPL are pretty minimal.

That's why we use safety factors. 5% is a whole load less than what the CAA mandate adding on when calculating take off or landing distances.

Here's the relevant safety sense leaflet.

http://www.caa.co.uk/docs/33/ga_srg_09webSSL07.pdf

[Pilot DAR]

it will deteriorate with time and in terms of wings/fuselage airflow will be affected

Deteriorate, maybe to the extent of the paint looking poor, or being cracked, which is likely to affect performance in a small way. On bare aluminum, perhaps a bit of very minor surface corrosion, which does not affect strength (and certainly not airflow).

Other than that, anything which has happened to the aircraft which would affect the airflow in any detectable way, renders the aircraft unairworthy, and in need of repair.

Cessna does provide provisions for patching small damage in certain areas, but any large damage requires the replacement of the affected part(s). There is a very clear description in the maintenance manual of what to do with damage, and if followed properly, the aircraft will not be at all aerodynamically defective.

Therefore, an aircraft maintained in accordance with the maintenance manual will continue to meet the terms specified in it's Type Certificate Data Sheet - indefinately. Anything else would completely undermine the basis of defining and approving a design, and the definition of "airworthy" would have no meaning.

[gasax]

This thread has taken a slightly depressing turn. Full marks to Pilot DAR for trying to keep a little intelligence going!

I suppose some of it is the near complete ignorance most UK PPLs have of the POH and aircraft maintenance in general. No wonder so many of them are easy meat for the so called engineering organisations!


If you conduct a flight test for a CAA CofA aircraft the MAXIMUM loss of performance you are allowed in the climb test is 40 ft/min. Any more and the aircraft will not get a CofA. These things should be known by all PPLs - after all this is what we all depend upon to reach the performance figures upon which we all rely. There are similar tolerances for stall speed etc. Overall any rewal deterioration in performance - which would be obvious to PPLs - prohibit the issue of a CofA.

Incidents like the recent Sandown accident where aircraft performance deterioration were probably a factor have lead the CAA to restate their position on performance testing, which has been eased off significantly by EASA. So the situation for EASA CofA aircraft is that without performance testing for every CofA they may deteriorate to the point that people have speculated about in this thread.

[Say again s l o w l y]

There is a massive difference between aircraft of the same type most of the time. Even ones that rolled off the production line one after another, let alone after umpteen thousand heavy landings and variable maintenance. Mind you my experience of brand new aircraft is limited to things made in France, so I'd believe anything really!

It's a sad fact of life that performance figures in POH's are often not achieveable. I have flown many aircraft where I cannot believe they have got through their air tests, but back from the engineering shop they come with nice new bits of paper.

How many PPL's even know about checking performance on takeoff? Let alone knowing what is or isn't acceptable in flight? Given the fact that so many seem to have no idea what the POH even looks like, then I almost despair.

[Big Pistons Forever]

To achieve near book performance the aircraft must be flown very accurately.
For example best rate of climb must be flown exactly on speed. Even 2 knots higher or lower will measureably effect ROC as will not having the wings level and the ball perfectly in the middle. If the aircraft is not doing what it is supposed to, the first place to look is flying technique.

[Say again s l o w l y]

My only answer to that is no sh*t sherlock!! ;)