View Full Version : Boeing says No Technical Objection. Does this mean you are on your own?

23rd Apr 2006, 14:26
Using the B737 series as an example, it is a fact that some operators do not necessarily follow the FCTM procedures for a rejected take off procedure.
By this I mean the order in which actions are carried out by the captain. Boeing recommend manual speed brake action before use of reverse thrust. Some operators disagree with the Boeing advice and rely on the reverse thrust levers to actuate the automatic speed brake action. If the automatic function should fail, there is a possibility valuable stopping distance is lost until the speed brake is re-selected manually.

My understanding is that operators who deliberately change a Boeing recommended procedure to suit themselves should notify the manufacturer who in turn issues an NTO or No technical Objection.

Does this in effect mean Boeing washes its hands of any responsibility should an accident occur where their recommendation was not followed due to company procedure? Put another way, if the captain is aware (in this example the abort procedure) the FCTM says one thing and the company says another, and an accident occurs, is he liable to be hung out to dry for not conforming to the Boeing advice even though a NTO has been issued by Boeing?

Mad (Flt) Scientist
23rd Apr 2006, 18:58
Its basically impossible for an OEM to "wash their hands" of any responsibility, no matter what they do. Even if a crew were to go against every single procedure in the book, you'd find someone trying on the "but they should have catered for this anyway" line.

What the NTO is doing is basically saying "the OEM disagrees that this is the best procedure, but it won't in itself break the systems". Since this company-specific procedure is presumably covered by the company SOPs and approved by the local airworthiness authority through that route, the crew are hardly 'on their own' in any case.

24th Apr 2006, 08:02
NTO's are very common in Engineering.

Work that is accomplished IAW the MM, the SRM or an SB is usually FAA approved. (a few SB's are not but none in recent years.:bored: )
For work not currently in any manuals, like a repair that is outside the SRM, or deviation from a mod, many Airworthiness Authorities require the approval to come from the FAA and if this is the case it then requires an FAA form 8110.
The 8110 is actually certified by a Designated FAA engineer (DER) and are dealt with in a more involved way. If the Authority accepts an NTO then this is the easier route for the manufacturer.
It means that the manufacturer is happy but has not put it through the full FAA papermill procedure.:}

24th Apr 2006, 14:02
basically I agree with most of the above. The manufacturer has a responsibility to warn of unsafe practices. Thus if Boeing had reason to believe that the alternate practice would be unsafe they would not issue an NTO statement.

Even after issuing an NTO statement, Boeing could still carry some liability if they should have known the alternate procedure was likely to be unsafe.

24th Apr 2006, 14:36
It's been a few yrs since I was involved with Boeing products but I think if you take a close look at the front matter in the FCOM or FCTM you'll find a statement stating something to the effect that the procedures therein are "recommended" and operators may deviate as they see fit. There is no need to notify Boeing. (It's there somewhere)

You will usually need an NTO if you deviate from an AFM procedure though.

In practice I experence this issue regularly and can confirm that the same applies for Airbus, Douglas, De havilland, and Canadair. I have been taken to task on the NTO issue once in a while by regulatory authourities and I usually just dig out the reference stated above to quiet their concerns. Works like a charm.

4th May 2006, 15:02
Many thanks for your replies. Observed a sim session where the instructor disabled the automatic speed brake function prior to departure. In other words the speed brake lever would not actuate automatically only manually. When the crew was given a rejected take off around 110 knots, the captain hauled in reverse thrust and both pilots failed to twig the speed brake had not actuated. The "aircraft" over ran the runway because of lack of max braking until too late.

On the other hand the FCTM requires manual selection of the speed brakes on commencement of an abort and if the pilot forgets to pull the speed brake, then when he applies reverse this will automatically actuate the speed brake. In other words the auto speed brake via reverse levers is the vital back-up to the manual actuation. Makes one wonder why some operators choose to disregard the manufacturers recommendations or do not adequately research why the manufacturer recommends certain actions.

5th May 2006, 13:09
You are right.
The calculation for balance field considers max braking (manual or RTO) with no delay for braking or speedbrakes actuation.It does not considers use of reverse thrust:' Baseline: AFM balance field length== All engine RTO,brakes and speedbrakes only,no thrust reverse "
So ,one should follow FCTM procedure,which says : close thrust levers,aplly max brakes (or vrify RTO autobrakes) ,then raise speedbrake lever.
After that apply max reverse thrust consistent with conditions.
Failure to raise the speedbrake can give a penalty of +630' (no reverse) or +310' (one thrust reverser)

5th May 2006, 13:42
Good posts above.. I'd also add that most (all?) Boeings consider reverse thrust as 'free' as far as landing performance is concerned. Another important reason for deploying the speed brakes after retarding the thrust levers is that they are most effective at higher speeds and you are in effect transferring more weight (energy) to the brakes which should be shouldering most of the work (max brakes). Two (maybe 2.5) thrust reversers are much less significant/effective than max brakes and speed brakes.

In the US, the FAA can't hang the crew if they perform per the company SOP even if the SOP is different than the Boeing method.

I'm no fan of high speed rejects myself but v1 is there for a reason. :8

5th May 2006, 16:55
At Lockheed we used the "No thechnical objection" (NTO) statement for years. However, about 15 years ago the FAA said that they would no longer accept the NTO's, without explanations of what could happen.

On the L-1011 a fairly common problem (happened maybe 10 times in the twenty years I worked in product support) where the mounting structure for the No. 2 spoiler would fail. If it failed at an outstation we would issue a NTO to allow the aircraft to be ferried to a repair facility. But 15 years ago that was no longer acceptable. We still issued the NTO but added things like; all broken parts have to be securred, No. 2 spoilers must be shutoff on the PFCS panel, this ports hydraulic fluid to the retract side of the spoiler actuator and prevents spoiler float in flight, the crew should be advised the use of auto spoilers on landing is permissable, but the nose of the aircarft may pitch up upon spoiler deployent. Therefore, manual spoiler operation is recommended. There were more but I can't remember them all.